Câu 7:
\(\frac{4x-4}{2x\left(x+3\right)}\)
\(=\frac{\left(4x-4\right)\cdot3\cdot\left(x+1\right)}{2x\left(x+3\right)\cdot3\cdot\left(x+1\right)}=\frac{12\left(x-1\right)\left(x+1\right)}{6x\left(x+3\right)\left(x+1\right)}\)
\(=\frac{12x^2-12}{6x\left(x+3\right)\left(x+1\right)}\)
\(\frac{x-3}{3x\left(x+1\right)}\)
\(=\frac{\left(x-3\right)\cdot2\cdot\left(x+3\right)}{3x\left(x+1\right)\cdot2\cdot\left(x+3\right)}=\frac{2\left(x^2-9\right)}{6x\left(x+1\right)\left(x+3\right)}\)
\(=\frac{2x^2-18}{6x\left(x+1\right)\left(x+3\right)}\)
Câu 6:
\(\frac{5x+10}{25x^2+50x}\)
\(=\frac{5\left(x+2\right)}{25x\left(x+2\right)}\)
\(=\frac{5}{25x}=\frac{1}{5x}\)
