a[a+2b]-[a+1]²+2a先化简,在求值a=2,b=二分之一

问题描述:

a[a+2b]-[a+1]²+2a先化简,在求值a=2,b=二分之一

原式=a²+2ab-a²-2a-1+2a
=2ab-1
=2×2×(1/2)-1
=2-1
=1