Giúp mk một vài câu vs!!
Bài 5:
5) (\(\dfrac{4}{13}\) .\(\dfrac{6}{5}\)+\(\dfrac{4}{13}\).\(\dfrac{2}{5}\))(2x+1)2=\(\dfrac{10}{13}\)
6)3.22x+1+\(\dfrac{1}{2}\) =\(\dfrac{49}{2}\)
7)\(\dfrac{1}{21}\) +\(\dfrac{1}{28}\)+\(\dfrac{1}{36}\) +.....+\(\dfrac{2}{x\left(x+1\right)}\) =\(\dfrac{2}{9}\)
8)\(|x-2|\) -\(\dfrac{3}{7}\) \(|x-2|\) +\(\dfrac{3}{4}\) = 2\(|x-2|\) -\(\dfrac{-8}{7}\)
Bài 7:Tìm x,y,z biết \(\dfrac{x}{6}\)=\(\dfrac{y}{9}\);x=\(\dfrac{z}{2}\) và x+y+z=27
nhanh nha!!