Question

Câu 1. (2 điểm): Phân tích các đa thức sau thành nhân tử:

a) $5 x^3-45 x$;

b) ${x}^2-7 {x}+12$.

Answer 1

a. 5x(x-3)(x+3)

b. (x-3)(x-4)

Answer 2

a. \(5x\left(x^2-9\right)\)

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

b.\(x^2-4x-3x+12\)

= \(\left(x^2-4x\right)-\left(3x-12\right)\)

\(=x\left(x-4\right)-3\left(x-4\right)\) 

= \(\left(x-3\right)\left(x-4\right)\)

Answer 3

5x(x-3)(x+3)

Answer 4

a ) 5x³-45x

= 5 x.x.x - 5x.9

=5x²(x-9)

b x²-7x+12

= x²+6²-7x

=12x²-7x

 

Answer 5

5x(x2-9?")=5x x-3 x|||||\==+3

 

Answer 6

a) 5x³ - 45x
= x. ( 5x² - 45)

Answer 7

a,5x³-45x=5x(x²-9)

b,x²-7x+12=x²-3x-4x+12=(x²-3x)-(4x-12)=x(x-3)-4(x-3)=(x-3)(x-4)

Answer 8

a) 5x³-45x

=5x(x²-9)

=5x(x+3)(x-3)

b) x²-7x+12

=x²-3x-4x+12

=(x²-3x)-(4x-12)

=x(x-3)-4(x-3)

=(x-3)(x-4)

Answer 9

a) 5x(x-3)(x+3)

b)(x^2-6x+9)-(x-3)

=(x-3)^2-(x-3)

=(x-3)(x-4)

 

Answer 10

a)5x(x2-15)