若a³-ab+2b²=3则2ab-2a²-4b²-7=
问题描述:
若a³-ab+2b²=3则2ab-2a²-4b²-7=
答
2ab-2a²-4b²-7=-2(a²-ab+2b²)-7=-2×3-7=-13
若a³-ab+2b²=3则2ab-2a²-4b²-7=
2ab-2a²-4b²-7=-2(a²-ab+2b²)-7=-2×3-7=-13