已经a+b=1,ab=-3,求2a³b+2ab³
问题描述:
已经a+b=1,ab=-3,求2a³b+2ab³
答
解
2a³b+2ab³
=2ab(a²+b²)
=2ab[(a+b)²-2ab]
=2×(-3)[1²-2×(-3)]
=-6(1+6)
=-6×7
=-42