Question

Phân tích đa thức thành nhân tử:

a) x³-5x²-14x

b) x⁴ +4x²-5

c) x²-7x+14

d) x² - x -72

e) x²- 7xy + 10y²

Answer 1

a) \(x^3-5x^2-14x\)

\(=x^3+2x^2-7x^2-14x\)

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

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

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

b) \(x^4+4x^2-5\)

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

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

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

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

c) Hình như sai đề

Answer 2

c: Sửa đề: x^2-7x+10

=x^2-2x-5x+10

=(x-2)(x-5)

d: =x^2-9x+8x-72

=(x-9)(x+8)

e: =x^2-2xy-5xy+10y^2

=x(x-2y)-5y(x-2y)

=(x-2y)(x-5y)