Question

x y=10, xy=21 evaluate x^3-y^3
solution with explanation

Answer 1

X^3 - Y^3 = (X-Y) (X^2 +Y^2 + XY)
And
(X-Y)^2 = X^2 + Y^2 - 2XY
Put the given values of equation, we get
10^2 = X^2 + Y^2 - 2*21
X^2 + Y^2 = 100+42 = 142
now,
X^3 - Y^3 = 10*(142 + 21)
= 10*163 = 1630