Question

giúp mik với ạ 
Mai mik thi rồi

Answer 1

Câu 15:

a: \(=\dfrac{x+4-3x}{x-2}=\dfrac{-2x+4}{x-2}=-2\)

b: \(=\dfrac{10}{\left(x-5\right)\left(x+5\right)}-\dfrac{5}{x\left(x+5\right)}\)

\(=\dfrac{10x-5x+25}{x\left(x+5\right)\left(x-5\right)}=\dfrac{5\left(x+5\right)}{x\left(x+5\right)\left(x-5\right)}=\dfrac{5}{x\left(x-5\right)}\)