Question

(2/3)^3-4.(-1 3/4)^2+(-2/3)^3

giúp mình vs ạ :))

Answer 1

= \(\left(\dfrac{2}{3}\right)^3-4.\left(-\dfrac{7}{4}\right)^2+\left(-\dfrac{2}{3}\right)^3\)

= \(\dfrac{8}{27}-4.\dfrac{49}{16}+\left(-\dfrac{8}{27}\right)\)

= \(\left[\dfrac{8}{27}+\left(-\dfrac{8}{27}\right)\right]-4.\dfrac{49}{16}\)

= \(-\dfrac{49}{4}\)

Answer 2

   \(\left(\dfrac{2}{3}\right)^3-4.\left(-1\dfrac{3}{4}\right)^2+\left(\dfrac{-2}{3}\right)^3\)

= \(\left[\left(\dfrac{2}{3}\right)^3+\left(\dfrac{-2}{3}\right)^3\right]-4.\left(-1\dfrac{3}{4}\right)^2\)

= \(\left(\dfrac{8}{9}+\dfrac{-8}{9}\right)-4.\left(-1\dfrac{3}{4}\right)^2\)

= \(0-4.\left(\dfrac{-7}{4}\right)^2\)

= \(0-4.\dfrac{49}{16}\)

= \(0-\dfrac{49}{4}\)

= \(\dfrac{-49}{4}\)