bài 3
a) \(=\left(a-2y\right)\left(a+2y\right)\)
b) \(=\left(x-6\right)\left(x+6\right)\)
c) \(=\left(x+2\right)\left(x^2-2x+4\right)\)
d) \(=\left(3x-1\right)\left(9x^2+6x+1\right)\)
bài 4
a) \(=\left(100-2\right)^2=100^2-2\cdot100\cdot2+4=9604\)
b) \(=\left(100+3\right)^2=100^2+2\cdot100\cdot3+3^2=10609\)
c) \(=\left(60-3\right)\left(60+3\right)=60^2-9=3591\)
d) \(=\left(100-2\right)\left(100+2\right)=100^2-4=9996\)