7.若a2+a=-1,则a4+2a3-3a2-4a+3的值为 [ ] A.8 B.7 C.10 D.12
问题描述:
7.若a2+a=-1,则a4+2a3-3a2-4a+3的值为 [ ] A.8 B.7 C.10 D.12
答
a4+2a3-3a2-4a+3=(a2+a)²-4(a2+a)+3=8,选A.
7.若a2+a=-1,则a4+2a3-3a2-4a+3的值为 [ ] A.8 B.7 C.10 D.12
a4+2a3-3a2-4a+3=(a2+a)²-4(a2+a)+3=8,选A.