Question

10(a [в квадрате]-15)-12(a-4)(a+4)-42+ 2a[в квадрате]

Answer 1

10(а²-15)-12(а-4)(а+4)-42+2а²=10а²-150-12(а²-16)-42+2а²=10а²-150-12а²+192-12+2а²=0+0=0

Answer 2

$10(a^2-15)-12(a-4)(a+4)-42+2a^2= \ =10a^2-150-12(a^2-16)-42+2a^2= \ =12a^2-192-12a^2+192=0$