Bài 2:
b: \(=\left(x^2+x+4+3x\right)\left(x^2+x+4+5x\right)\)
\(=\left(x^2+4x+4\right)\left(x^2+6x+4\right)\)
\(=\left(x+2\right)^2\cdot\left(x^2+6x+4\right)\)
c: \(=25x^2-49y^2-\left(5x+7y\right)\)
=(5x+7y)(5x-7y-1)
d: \(8x^3-36x^2+54x-27=\left(2x-3\right)^3\)