Câu hỏi của nguyễn thọ hồng Quân

Question

Giải phép tính:1+3+5+7+...+1991+1993+1995

Nguyễn Trung Hiếu · Accepted Answer

Số các số hạng là:(1995-1):2+1=998 (số)Tổng của dãy số trên là:(1995+1)x998:2=996004 Đáp số: 996004.Câu trả lời: Số các số hạng là:(1995-1):2+1=998 (số)Tổng của dãy số trên là:(1995+1)x998:2=996004 Đáp số: 996004.

l҉o҉n҉g҉ d҉z҉ · Answer

<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992Câu trả lời: <=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992<=> 1/3 + 1/6 + 1/10 +...+ 1/x(x+1):2 = 1/1991/1993 - 1 = 1991/1993<=> 1/2(2+1):2 + 1/3(3+1):2 + ...+ 1/x(x+1):2 = 1991/1993<=> 1/2.3:2 + 1/3.4:2 +...+ 1/x(x+1):2 = 1991/1993<=>(1/2 - 1/3):1/2 + (1/3 - 1/4 ):1/2+...+(1/x-1/x+1):1/2=1991/1993<=>(1/2-1/3).2 + (1/3-1/4).2+...+(1/x-1/x+1).2 = 1991/1993<=>2.(1/2-1/3+1/3-1/4+1/4-1/5+....+1/x-1/x+1)=1991/1993<=>2.(1/2-1/x+1)=1991/1993<=>1/2-1/x+1=1991/1993:2=1991/3986<=> 1/x+1=1/2-1991/3986=2/3986=1/1993=>x=1993-1=1992

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