Question

Bài 3: cho biểu thức

a) tìm đkxđ, rút gọn p

b) tìm x để p>10

P=\(\dfrac{2\left(x^2+1\right)}{x^2-3x-4}+\dfrac{x}{X+1}-\dfrac{8}{x-4}\)

Answer 1

a) P = \(\dfrac{2\left(x^2+1\right)}{x^2-3x-4}+\dfrac{x}{x+1}-\dfrac{8}{x-4}\) ( x # -1 ; x # 4)

P = \(\dfrac{2\left(x^2+1\right)}{x^2+x-4x-4}+\dfrac{x}{x+1}-\dfrac{8}{x-4}\)

P = \(\dfrac{2\left(x^2+1\right)}{\left(x+1\right)\left(x-4\right)}+\dfrac{x\left(x-4\right)}{\left(x+1\right)\left(x-4\right)}-\dfrac{8\left(x+1\right)}{\left(x-4\right)\left(x+1\right)}\)

P = \(2x^2+2+x^2-4x-8x-8\)

P = \(3x^2-12x-6\)