计算(a+3)(a-1)-a(a-2)
问题描述：
计算(a+3)(a-1)-a(a-2)
答
(a+3)(a-1)-a(a-2)
=a^2+2a-3-a^2+2a
=4a-3
答
(a+3)(a-1)-a(a-2)
=a^2+3a-a-3-a^2+2a
=4a-3