a-b-3=0,则2a²+4ab+2b²-6

a-b-3=0,则2a²+4ab+2b²-6
a-b-3=0,则2a²+4ab+2b²-6

a-b-3=0,则2a²+4ab+2b²-6
a-b-3=0
a-b=3
2a²-4ab+2b²-6
=2(a²-2ab+b²)-6
=2(a-b)²-6
=2×3²-6
=12
你确定题目的+-号都抄对了吗?