Question

giúp mình với, mình cảm ơn nhiều

Answer 1

a, \(A=\left(\dfrac{8}{3}xy^2\right).\left(\dfrac{-1}{4}x^2y^5\right).\left(10x^5y^7\right)^0\)

⇒\(A=\dfrac{8}{3}xy^2.\dfrac{-1}{4}x^2y^5.1\)

⇒\(A=\left(\dfrac{8}{3}.\dfrac{-1}{4}.1\right).\left(x.x^2\right).\left(y^2.y^5\right)\)

⇒\(A=\dfrac{-2}{3}x^3y^7\)

+)Hệ số: \(\dfrac{-2}{3}\)

+)Bậc:10

b, Thay \(x=2\), \(y=-1\) vào A ta có:

\(A=\dfrac{-2}{3}.2^3.\left(-1\right)^7\)

⇒\(A=\dfrac{-2}{3}.8.\left(-1\right)\)

⇒\(A=\dfrac{16}{3}\)

Vậy \(A=\dfrac{16}{3}\) khi \(x=2,y=-1\)