evaluate expressions

Question

Evaluate the  expression.  (a-b) (a^2+ab=b^2),  a = 10, b = -21.

Answer 1

Given a = 10, b = -21

Substitute the a,b values in given expression (a-b)(a^2+ab+b^2) .

Recall the formula (a-b)(a^2+ab+b^2) = a^3-b^3

a^3-b^3 = 10^3-(-21)^3

= 1000+9261

= 10261