\(a,=4x\left(x+3y\right)\\ b,=\left(x-5\right)\left(x+7\right)\\ c,=\left(x+1\right)^2-y^2=\left(x+y+1\right)\left(x-y+1\right)\\ d,=x^2\left(x^2-5\right)\)
a) \(=4x.x+4x.3y=4x\left(x+3y\right)\)
b) \(=\left(x-5\right)\left(x+7\right)\)
c) \(=\left(x^2+2x+1\right)-y^2=\left(x+1\right)^2-y^2=\left(x+1-y\right)\left(x+1+y\right)\)
d) \(=x^2.x^2-5x^2=x^2\left(x^2-5\right)\)
a, 4x2 + 12xy = 4x.(x + 3y)
b, x.(x - 5) + 7.(x - 5) = (x - 5). (x + 7)
c, x2 + 2x + 1 -y2 = (x + 1)2 - y2 = (x + 1 -y).(x + 1 + y)
d, x4 - 5x2 = x2.( x2 - 5 )
