Question

已知a+b=5,ab=3,求代数式a的三次方b+2a的平方b的平方+ab的三次方的值

Answer 1

∵a+b=5,ab=3
∴a^3b+2a^2b^2+ab^3
=ab(a^2+2ab+b^2)
=ab(a+b)^2
=3*5^2
=3*25
=75