Tìm x:a) 4 ( x - \(\frac{1}{2}\)) + ( 2 - x) . ( -2) = 3xb) ( x+1) . ( x-2) - (x - 1) . ( x+2) = 5c) ( x + 5) . ( x2 - 1) . ( x2 + 1) = 0d) ( \(\frac{1}{1\cdot2}\)+ \(\frac{1}{2\cdot3}\)+ \(\frac{1}{3\cdot4}\)+ .........+ \(\frac{1}{99\cdot100}\)) . ( x - 3) = 1e) ( \(\frac{1}{1\cdot3}\)+ \(\frac{1}{3\cdot5}\)+ \(\frac{1}{5\cdot7}\)+ .........+ \(\frac{1}{99\cdot101}\)) . ( x +2 )...
Đọc tiếp
Tìm x:
a) 4 ( x - \(\frac{1}{2}\)) + ( 2 - x) . ( -2) = 3x
b) ( x+1) . ( x-2) - (x - 1) . ( x+2) = 5
c) ( x + 5) . ( x2 - 1) . ( x2 + 1) = 0
d) ( \(\frac{1}{1\cdot2}\)+ \(\frac{1}{2\cdot3}\)+ \(\frac{1}{3\cdot4}\)+ .........+ \(\frac{1}{99\cdot100}\)) . ( x - 3) = 1
e) ( \(\frac{1}{1\cdot3}\)+ \(\frac{1}{3\cdot5}\)+ \(\frac{1}{5\cdot7}\)+ .........+ \(\frac{1}{99\cdot101}\)) . ( x +2 ) = \(\frac{3}{101}\)
Mình chỉ làm cho bạn câu d và e thôi
d) ( 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 +....... +1/99 - 1/100 ) . (x - 3)=1
( 1 - 1/100 ) . (x - 3 )=1
99/100.(x -3)=1
x - 3 = 1:99/100
x - 3 =100/99
x = 100/99 + 3
x = 397/99
e) (1/2 . (1 - 1/3 + 1/3 - 1/5 + 1/5 -1/7 +.....+1/99 - 1/101 ) . (x+2) =3/101
(1/2 . ( 1 - 1/101 ).(x+2)=3/101
(1/2 . 100/101 ) . (x + 2) =3/101
100/202 . ( x + 2 )= 3/101
50/101 . (x + 2 ) = 3/101
x + 2 = 3/101 :50/101
x+2=3/50
x =3/50-2
x= -97/100