(b-4)*(b+2)-(b-1)^2 упростить

Question

(b-4)*(b+2)-(b-1)^2 упростить

Answer 1

(b-4)*(b+2)-(b-1)^2 = b2-2b-8-b2+2b-1=-9

Answer 2

(b-4)*(b+2)-(b-1)^2=

b^2+2b-4b-8 - (b^2-2b+1)=

b^2+2b-4b-8-b^2+2b-1=

0=9

b∈ R