Question

已知a+b=3,ab=2,求a的三次方乘b+2a的2次方b的2次方+a乘b的三次方的值

Answer 1

a^3b+2a^2b^2+a*b^3=a^2(ab)+2(ab)^2+b^2(ab)

=2a^2+2*2^2+2b^2

=8+2(a^2+b^2)

=8+2[(a+b)^2-2ab]

=8+2(9-4)

=18