Question

Answer 1

Bài 12A:

a: Ta có: \(x^2+2x-8\)

\(=x^2+4x-2x-8\)

\(=x\left(x+4\right)-2\left(x+4\right)\)

\(=\left(x+4\right)\left(x-2\right)\)

b: Ta có: \(x^2+5x+6\)

\(=x^2+2x+3x+6\)

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

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

c: Ta có: \(4x^2-12x+8\)

\(=4x^2-4x-8x+8\)

\(=4x\left(x-1\right)-8\left(x-1\right)\)

\(=4\left(x-1\right)\left(x-2\right)\)

d: Ta có: \(x^2+8xy-9y^2\)

\(=x^2+9xy-xy-9y^2\)

\(=x\left(x+9y\right)-y\left(x+9y\right)\)

\(=\left(x+9y\right)\left(x-y\right)\)

Answer 2

Bài 13A:

a: Ta có: \(x^2+6x+8\)

\(=x^2+2x+4x+8\)

\(=x\left(x+2\right)+4\left(x+2\right)\)

\(=\left(x+2\right)\left(x+4\right)\)

b: Ta có: \(x^2+14x+13\)

\(=x^2+x+13x+13\)

\(=x\left(x+1\right)+13\left(x+1\right)\)

\(=\left(x+1\right)\left(x+13\right)\)

c: Ta có: \(9x^2+24x+15\)

\(=9x^2+9x+15x+15\)

\(=9x\left(x+1\right)+15\left(x+1\right)\)

\(=3\left(x+1\right)\left(3x+5\right)\)

d: Ta có: \(6x^2-xy-7y^2\)

\(=6x^2-7xy+6xy-7y^2\)

\(=x\left(6x-7y\right)+y\left(6x-7y\right)\)

\(=\left(6x-7y\right)\left(x+y\right)\)