Question

thực hiện các phép tính

a.\(\dfrac{4y^2}{11x^4}:\left(-\dfrac{8y}{33x^2}\right)\)

b.\(\dfrac{x^2-4}{3x+12}.\dfrac{x+4}{2x-4}\)

Answer 1

a) \(\dfrac{4y^2}{11x^4}:\left(-\dfrac{8y}{33x^2}\right)\)

\(=\dfrac{4y^2}{11x^4}.\left(-\dfrac{33x^2}{8y}\right)\)

\(=-\dfrac{4y^2.33x^2}{11x^4.8y}\)

\(=-\dfrac{3y}{2x^2}\)

b) \(\dfrac{x^2-4}{3x+12}.\dfrac{x+4}{2x-4}\)

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

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

\(=\dfrac{x+2}{6}\).

Answer 2

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