a: Thay x=25 vào Q, ta được:\(Q=\dfrac{2\cdot5-2}{5+3}-1=1-1=0\)b: \(=\dfrac{24+\left(x-4\right)\left(x+3\right)-\left(x-1\right)\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)\(=\dfrac{24+x^2-x-12-x^2+4x-3}{\left(x-3\right)\left(x+3\right)}\)\(=\dfrac{3x-9}{\left(x-3\right)\left(x+3\right)}=\dfrac{3}{x+3}\)Câu trả lời: a: Thay x=25 vào Q, ta được:\(Q=\dfrac{2\cdot5-2}{5+3}-1=1-1=0\)b: \(=\dfrac{24+\left(x-4\right)\left(x+3\right)-\left(x-1\right)\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)\(=\dfrac{24+x^2-x-12-x^2+4x-3}{\left(x-3\right)\left(x+3\right)}\)\(=\dfrac{3x-9}{\left(x-3\right)\left(x+3\right)}=\dfrac{3}{x+3}\)