Question

Qui đồng mẫu thức các phân thức:

\(\dfrac{x}{x^2+2x-15};\dfrac{1}{x^2+5x-6}\) và \(\dfrac{1}{-x^2+4x-3}\)

Answer 1

MTC=(x-1)(x-3)(x+6)(x+5)

\(\dfrac{x}{x^2+2x-15}=\dfrac{x}{\left(x+5\right)\left(x-3\right)}=\dfrac{x\left(x-1\right)\left(x+6\right)}{\left(x+5\right)\left(x-3\right)\left(x+6\right)\left(x-1\right)}\)

\(\dfrac{1}{x^2+5x-6}=\dfrac{1}{\left(x+6\right)\left(x-1\right)}=\dfrac{\left(x-3\right)\left(x+5\right)}{\left(x-1\right)\left(x-3\right)\left(x+5\right)\left(x+6\right)}\)

\(\dfrac{1}{-x^2+4x-3}=-\dfrac{1}{\left(x-1\right)\left(x-3\right)}=\dfrac{-\left(x+5\right)\left(x+6\right)}{\left(x-1\right)\left(x-3\right)\left(x+5\right)\left(x+6\right)}\)