Question

  giải giúp mình với ạ

Answer 1

a: ĐKXĐ: \(x\notin\left\{2;-2\right\}\)

b: \(A=\dfrac{3}{x-2}-\dfrac{12}{x^2-4}\)

\(=\dfrac{3}{x-2}-\dfrac{12}{\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{3\left(x+2\right)-12}{\left(x-2\right)\left(x+2\right)}=\dfrac{3x-6}{\left(x-2\right)\left(x+2\right)}=\dfrac{3}{x+2}\)

c: Khi x=4 thì \(A=\dfrac{3}{4+2}=\dfrac{3}{6}=\dfrac{1}{2}\)