若2a²-a-3=0,则5+2a²=
问题描述：
若2a²-a-3=0,则5+2a²=
答
2a²-a-3=0
(2a-3)(a+1)=0
解得
a= - 1 或 a = 1.5
当a= - 1 时
5+2a²
=5+2
=7
当a = 1.5时
5+2a²
=5+4.5
=9.5
答
2a²-a-3=0
(a+1)(2a-3)=0
a1=-1,a2=1.5
当a=-1时,5+2a²=5+2×1=7
当a=1.5时,5+2a²=5+2×2.25=9.5