Question

tim 1x biet 

9/20+9/30+9/42+...+9/2(x+1)=3/2

 

Answer 1

=>\(\left(\frac{9}{20}+\frac{9}{30}+\frac{9}{4}+111\right)+\frac{9}{2}\left(x+1\right)=\frac{3}{2}\)

=>\(114+\frac{9}{2}\left(x+1\right)=\frac{3}{2}\)

=>\(\frac{9}{2}\left(x+1\right)=\frac{-111}{2}\)

=>x+1=\(-\frac{37}{3}\)

=>x=\(-\frac{40}{3}\)