a) Ta có : 64x2 - (8x + y)2
= (8x)2 - (8x + y)2
= (8x - 8x - y) (8x + 8x + y)
= -y(16x + y)
Bài 1:
a)\(64x^2-(8x+y)^2=-y\left(16x+y\right)\)
b)\((x+y+15)^2-2(x+y+15)+1\)
\(=\left(x+y+14\right)^2\)
c)\(8x^3+60x^2y+150xy^2+125y^3\)
\(=\left(2x+5y\right)^3\)
d)\(x^{16}-1\)
\(=\left(x-1\right)\left(x+1\right)\left(x^2+1\right)\left(x^4+1\right)\left(x^8+1\right)\)
Bài 2:
\(\left(n+7\right)^2-\left(n-5\right)^2\)
\(=\left(n+7+n+5\right)\left(n+7-\left(n+7\right)\right)\)
\(=24\left(n+1\right)\) chia hết 24