1.a=(-7x²+10x+12)+(4x²-5x-6)
2.(a²+ab)-(ab-b²)=a²+b²=20-(-13)=33
(a²+ab)+(ab-b²)=a²+2ab-b²=20+(-13)=7
初一简单数学题两道~~~~~~~急~~~~~~~~~~~~~
1.a=(-7x²+10x+12)+(4x²-5x-6)
2.(a²+ab)-(ab-b²)=a²+b²=20-(-13)=33
(a²+ab)+(ab-b²)=a²+2ab-b²=20+(-13)=7