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5 tháng 12 2018

\(P=\left(2+\sqrt{3}\right)^{-2017}.\left(2+\sqrt{3}\right)^{2018} \)
\(P=\left(2+\sqrt{3}\right)^{-2017+2018}\)
\(P=2+\sqrt{3}\)

8 tháng 5 2018

\(A=\frac{\frac{2017}{1}+\frac{2016}{2}+\frac{2015}{3}+...+\frac{1}{2017}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2018}}\)

\(A=\frac{1+\left(1+\frac{2016}{2}\right)+\left(1+\frac{2015}{3}\right)+...+\left(1+\frac{1}{2017}\right)}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2018}}\)

\(A=\frac{\frac{2018}{2018}+\frac{2018}{2}+\frac{2018}{3}+...+\frac{2018}{2017}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2018}}\)

\(A=\frac{2018\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2017}+\frac{1}{2018}\right)}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2018}}\)

\(A=2018\)

8 tháng 5 2018

Ta có : 

\(A=\frac{\frac{2017}{1}+\frac{2016}{2}+\frac{2015}{3}+...+\frac{1}{2017}}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2018}}\)

\(A=\frac{\left(\frac{2017}{1}-1-1-...-1\right)+\left(\frac{2016}{2}+1\right)+\left(\frac{2015}{3}+1\right)+...+\left(\frac{1}{2017}+1\right)}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2018}}\)

\(A=\frac{\frac{2018}{2018}+\frac{2018}{2}+\frac{2018}{3}+...+\frac{2018}{2017}}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2018}}\)

\(A=\frac{2018\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2018}\right)}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2018}}\)

\(A=2018\)

Vậy \(A=2018\)

Chúc bạn học tốt ~ 

15 tháng 10 2018

\(M=\left(2018^{2019}+2018^{2018}+...+2018^2+2018\right)2017+1\)

Gọi \(A=2018^{2019}+2018^{2018}+...+2018^2+2018\)

\(\Rightarrow2018A=2018^{2020}+2018^{2019}+...+2018^3+2018^2\)

\(\Rightarrow2018A-A=2018^{2020}-2018\)

\(\Rightarrow2017A=2018^{2020}-2018\)

\(\Rightarrow A=\left(2018^{2020}-2018\right)\div2017\)

\(\Rightarrow M=\left(2018^{2020}-2018\right)\div2017.2017+1\)

\(\Rightarrow M=2018^{2020}-2018+1\)

\(\Rightarrow M=2018^{2020}-2017\)

13 tháng 10 2018

Sai đề câu E sửa lại 95 hoặc 93 vì đây là dãy số mũ lẻ. Ta có : 

\(E=3+3^3+3^5+3^7+...+3^{95}\)

\(\Rightarrow\) \(9E=3^3+3^5+3^7+3^9+...+3^{95}+3^{97}\)

\(\Rightarrow\) \(8E=3^{97}-3\)

\(\Rightarrow\) \(E=\frac{3^{97}-3}{8}\)

13 tháng 10 2018

\(E=3+3^3+3^5+3^7+.......+3^{95}\)

\(\Rightarrow9E=3^3+3^5+3^7+3^9+...+3^{97}\)

\(\Rightarrow9E-E=\left(3^3+3^5+3^7+3^9+....+3^{97}\right)-\left(3+3^3+3^5+3^7+.....+3^{95}\right)\)

\(\Rightarrow8E=3^{97}-3\)

\(\Rightarrow E=\frac{3^{97}-3}{8}\)

\(F=1+2018+2018^2+......+2018^{2017}\)

\(=2018^0+2018^1+2018^2+....+2018^{2017}\)

\(\Rightarrow2018F=2018^1+2018^2+2018^3+....+2018^{2018}\)

\(\Rightarrow2018F-F=\left(2018^1+2018^2+2018^3+....+2018^{2018}\right)-\left(2018^0+2018^1+2018^2+....+2018^{2017}\right)\)

\(\Rightarrow2017F=2018^{2018}-1\)

\(\Rightarrow F=\frac{2018^{2018}-1}{2017}\)

20 tháng 8 2018

Đặt \(D=1^2+2^2+3^2+...+2018^2\)

\(D=1\left(2-1\right)+2\left(3-1\right)+3\left(4-1\right)+...+2018\left(2019-1\right)\)

\(D=1.2-1+2.3-2+3.4-3+...+2018.2019-2018\)

\(D=\left(1.2+2.3+...+2018.2019\right)-\left(1+2+3+...+2018\right)\)

Đặt \(A=1.2+2.3+...+2018.2019\)

\(\Rightarrow3A=1.2.3+2.3.\left(4-1\right)+...+2018.2019\left(2020-2017\right)\)

\(\Rightarrow3A=2018.2019.2010\Rightarrow A=\frac{2018.2019.2020}{3}\)

Đặt \(B=1+2+3+...+2018\)

\(B=\frac{\left(2018+1\right)\left(2018-1+1\right)}{2}=\frac{2019.2018}{2}\)

\(\Rightarrow D=A+B=\frac{2018.2019.2020}{3}+\frac{2019.2018}{2}\)

\(\Rightarrow D=\frac{2018.2019.2020.2+2019.2018.3}{6}\)

17 tháng 10 2021

Đề lỗi không?

13 tháng 6 2018

\(A=\left(3m+4n-5p\right)-\left(3m-4n-5p\right)\)

\(\Rightarrow3m+4n-5p-3m+4n+5p=A\)

\(\Rightarrow A=\left(3m-3m\right)+\left(4n+4n\right)-\left(5p-5p\right)\)

\(\Rightarrow A=0+8n+0=8n\)

26 tháng 2 2020

Giúp mình nhen