Question

Phân tích các đa thức sau thành nhân tử:

a) x² + 5x + 4

b) 3x² + 4x - 7

c) x² + 7x + 12

Answer 1

a) \(x^2+5x+4==x\left(x+1\right)+4\left(x+1\right)=\left(x+1\right)\left(x+4\right)\)

b) \(3x^2+4x-7=3x\left(x-1\right)+7\left(x-1\right)=\left(x-1\right)\left(3x+7\right)\)

c) \(x^2+7x+12=x\left(x+3\right)+4\left(x+3\right)=\left(x+3\right)\left(x+4\right)\)

Answer 2

a) (x+1)(x+4)

b) (x-1)(3x+7)

c) (x+3)(x+4)

Answer 3

a) x²+5x+4 = x(x+4)+(x+4) = (x+4)(x+1)

b) 3x²+4x-7 = 3x(x-1)+7(x-1) = (x-1)(3x+7)

c) x²+7x+12 = x(x+4)+3(x+4) = (x+3)(x+4)

Answer 4

a: \(x^2+5x+4=\left(x+4\right)\left(x+1\right)\)

b: \(3x^2+4x-7=\left(3x+7\right)\left(x-1\right)\)

c: \(x^2+7x+12=\left(x+3\right)\left(x+4\right)\)