Question

Phân tích đa thức thành nhân tử.

a ) ( x² + x )² + 9x² + 9x + 14

b ) x² + 2xy + y² + 2x + 2y - 15

Answer 1

a,   \(\left(x^2+x\right)^2+9x^2+9x+14\)

\(=\left(x^2+x\right)^2+9\left(x^2+x\right)+14\)

\(=\left(x^2+x\right)^2+2\left(x^2+x\right)+7\left(x^2+x\right)+14\)

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

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

b,   \(x^2+2xy+y^2+2x+2y-15\)

\(=\left(x+y\right)^2+2\left(x+y\right)-15\)

\(=\left(x+y\right)^2+5\left(x+y\right)-3\left(x+y\right)-15\)

\(=\left(x+y\right)\left(x+y+5\right)-3\left(x+y+5\right)\)

\(=\left(x+y+5\right)\left(x+y-3\right)\)

Chúc bạn học tốt.