Question

Tính và rút gọn : (Mình cần gấp, giúp mình với ạ)

Answer 1

15: \(=\dfrac{x-4+3x+12+8}{\left(x-4\right)\left(x+4\right)}=\dfrac{4x+16}{\left(x-4\right)\left(x+4\right)}=\dfrac{4}{x-4}\)

16: \(=\dfrac{x-2+3+2x+4}{\left(x-2\right)\left(x+2\right)}=\dfrac{3x+5}{x^2-4}\)

17: \(=\dfrac{2x-4+2x+4-8}{2\left(x-2\right)\left(x+2\right)}=\dfrac{4x-8}{2\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{4\left(x-2\right)}{2\left(x-2\right)\left(x+2\right)}=\dfrac{2}{x+2}\)

19: \(=\dfrac{6x+30+6-2x+4x-20}{\left(x-5\right)\left(x+5\right)}=\dfrac{8x+16}{\left(x-5\right)\left(x+5\right)}\)

18: \(=\dfrac{2x-10+3x+15-x+3}{\left(x-5\right)\left(x+5\right)}=\dfrac{4x+8}{x^2-25}\)

20: \(=\dfrac{2\left(3x-2\right)-3x-2+4}{\left(3x-2\right)\left(3x+2\right)}\)

\(=\dfrac{6x-4-3x+2}{\left(3x-2\right)\left(3x+2\right)}=\dfrac{3x-2}{\left(3x-2\right)\left(3x+2\right)}=\dfrac{1}{3x+2}\)