已知a-b=2,求2a²+2b²-4ab-7的值
问题描述：
已知a-b=2,求2a²+2b²-4ab-7的值
答
2a^2+2b^2-4ab-7=2(a-b)^2-7=2X2^2-7=1
答
2a²+2b²-4ab-7
=2(a²+b²-2ab）-7
=2（a-b）²-7
=2×2²-7
=8-7
=1
答
2a²+2b²-4ab-7
=2(a²-2ab+b²)-7
=2(a-b)²-7
=2*2²-7
=8-7=1