Đáp án:
Giải thích các bước giải:
$b,(x+5)^2-2.(x+5)(x+7)+(x+7)^2$
$=(x+5-x-7)$
$=(-2)^2=4$
$c,(x-2)^3-x^2(x-6)=4$
$⇔x^3-6x^2+12x-8-x^3+6x^2=4$
$⇔(x^3-x^3)-(6x^2-6x^2)+12x=12$
$⇔12x=12$
$⇔x=1$
$d,(2x+y)(4x^2-2xy+y^2)-(2x-y)(4x^2+4xy+y^2)$
$=8x^3+y^3-8x^3+y^3$
$=2y^3$
$e,2.(3+1)(3^2+1)(3^4+1)(3^8+1)(3^{16}+1)$
$=(3-1)(3+1)(3^2+1)(3^4+1)(3^8+1)(3^{16}+1)$
$=(3^2-1)(3^2+1)(3^4+1)(3^8+1)(3^{16}+1)$
$=(3^4-1)(3^4+1)(3^8+1)(3^{16}+1)$
$=(3^8-1)(3^8+1)(3^{16}+1)$
$=(3^{16}-1)(3^{16}+1)$
$=(3^{32}-1)(3^{32}+1)$
$f,(x+3)(x^2-3x+9)-(54+x^3)$
$=x^3+27-54-x^3$
$=-27$
