.已知A=a2-2ab+b2,B=a2+2ab+b2,求:2a-3b

问题描述:

.已知A=a2-2ab+b2,B=a2+2ab+b2,求:2a-3b

2A-3B
=2(a²-2ab+b²)-3(a²+2ab+b²)
=2a²-4ab+2b²-3a²-6ab-3b²
=-a²-10ab-b²