化简求值:2(a-2)2-6a(a+2)+(a+2)(a-2),其中a=-2.
问题描述:
化简求值:2(a-2)2-6a(a+2)+(a+2)(a-2),其中a=-2.
答
2(a-2)2-6a(a+2)+(a+2)(a-2),
=2(a2-4a+4)-6a2-12a+a2-4,
=-3a2-20a+4,
当a=-2时,原式=-3×4+40+4=32.