【急!】a=1/2,求a²-3a+5+a²+2a-1

问题描述:

【急!】a=1/2,求a²-3a+5+a²+2a-1

解a²-3a+5+a²+2a-1
=2a^2-a+4
=2(1/2)^2-(1/2)+4
=1/2-1/2+4
=4