2(a-4)(a+3)-(2a-1)(a-1)

问题描述:

2(a-4)(a+3)-(2a-1)(a-1)

原式=2*(a^2-a-12)-(2a^2-3a+1)
=2a^2-2a-24-2a^2+3a-1
=(2-2)a^2+(3-2)a-24-1
=a-25