Question

cho \(A=\frac{x+1}{2015}+\frac{x+2}{2014}+\frac{x+3}{2013}+\frac{x+4}{2012}\)và B= -2² 

tìm x để A=B

Answer 1

            \(A=B\)

\(\Leftrightarrow\)\(\frac{x+1}{2015}+\frac{x+2}{2014}+\frac{x+3}{2013}+\frac{x+4}{2012}=-2^2\)

\(\Leftrightarrow\)\(\frac{x+1}{2015}+1+\frac{x+2}{2014}+1+\frac{x+3}{2013}+1+\frac{x+4}{2012}+1=0\)

\(\Leftrightarrow\)\(\frac{x+2016}{2015}+\frac{x+2016}{2014}+\frac{x+2016}{2013}+\frac{x+2016}{2012}=0\)

\(\Leftrightarrow\)\(\left(x+2016\right)\left(\frac{1}{2015}+\frac{1}{2014}+\frac{1}{2013}+\frac{1}{2012}\right)=0\)

\(\Leftrightarrow\)\(x+2016=0\)  (do  1/2015 + 1/2014 + 1/2013 + 1/2012  #  0)

\(\Leftrightarrow\)\(x=-2016\)

Vậy...

Answer 2

Trl 

-Bạn đường quỳnh trang làm đúng r

Học tốt 

nhé bn