a+b=7,ab=-3,a^2b^2=?
问题描述：
a+b=7,ab=-3,a^2b^2=?
答
ab=-3,a^2b^2=(ab)^2=(-3)^2=9;
a+b=7 (a+b)^2=a^2+b^2+2ab=49 a^2+b^2=14-2ab=49-2*(-3)=49+6=55