A2-b2 и a2-2ab+b2 при a=2; b=-5

Question

A2-b2 и a2-2ab+b2 при a=2; b=-5

Answer 1

A²-b²=(a-b)(a+b)=(2+5)(2-5)=7*(-3)=-21
a²-2ab+b²=(a-b)²=(2+5)²=7²=49

Answer 2

А²-b²=2²-(-5)²=4+25=29
a²-2ab+b²=(a-b)²=(2-(-5))²=(2+5)²=7²=49.