已知x+y=-3 xy=-5求x3+y3的值
问题描述:
已知x+y=-3 xy=-5求x3+y3的值
答
x^3+y^3
=(x+y)(x^2-xy+y^2)
=(x+y)[(x+y)^2-3xy]
=(-3)*[(-3)^2-3*(-5)]
=-72