Question

bài 1 : phân tích các đa thức sau thành nhân tử

a , 3x² - 3y²

b ^, x² - xy + 7x - 7y

c , x² - 3x + 2

d , x³ + 2x² y + xy² - 16x

Answer 1

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

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

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

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

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

d) \(x^3+2x^2y+xy^2-16x=x\left(x^2+2xy+y^2-16\right)\)

\(=x\left[\left(x+y\right)^2-16\right]=x\left(x+y-4\right)\left(x+y+4\right)\)