Question

a)  \(x^3+6x-7\) 

b)  \(4^2+8x-5\)

c)  \(9^2-4y^2+6x-4y\)

Answer 1

a) Ta có: \(x^3+6x-7\)

\(=x^3-x+7x-7\)

\(=x\left(x-1\right)\left(x+1\right)+7\left(x-1\right)\)

\(=\left(x-1\right)\left(x^2+x+7\right)\)

b) Ta có: \(4x^2+8x-5\)

\(=4x^2+10x-2x-5\)

\(=2x\left(2x+5\right)-\left(2x+5\right)\)

\(=\left(2x+5\right)\left(2x-1\right)\)

c) Ta có: \(9x^2-4y^2+6x-4y\)

\(=9x^2+6x+1-\left(4y^2+4y+1\right)\)

\(=\left(3x+1\right)^2-\left(2y+1\right)^2\)

\(=\left(3x+1+2y+1\right)\left(3x+2y\right)\)

\(=\left(3x+2y\right)\left(3x+2y+2\right)\)