Question

Answer 1

a)A= \(\dfrac{2x}{x-1}\)

thay x=3

=>A=\(\dfrac{2.3}{3-1}\)

=>A=3

b)\(\dfrac{x}{x+2}-\dfrac{x^3+8}{x^2-4}+\dfrac{3}{x-2}\)

\(\dfrac{\left(x-2\right).x}{\left(x+2\right)\left(x-2\right)}-\dfrac{\left(x^3+8\right)}{\left(x-2\right)\left(x+2\right)}+\dfrac{3\left(x+2\right)}{\left(x+2\right)\left(x-2\right)}\)

\(\dfrac{x^2-2x}{\left(x+2\right)\left(x-2\right)}-\dfrac{x^3+8}{\left(x-2\right)\left(x+2\right)}+\dfrac{3x+6}{\left(x-2\right)\left(x+2\right)}\)

\(\dfrac{x^2-2x-x^3-8+3x+6}{\left(x-2\right)\left(x+2\right)}\)

bn lm nốt nhá