Question

Phân tích các đa thức sau thành nhân tử :

a) x²-10x+9

b) x²-10x+16

c) x²-2x-8

d) 3x²-7x+2

Answer 1

a) x² - 10x + 9

= x² - x - 9x + 9

= (x² - x) - (9x - 9)

= x(x - 1) - 9(x-1)

= (x-1)(x-9)

b) x² - 10x + 16

= x² - 2x - 8x + 16

= (x² - 2x) - (8x - 16)

= x(x - 2) - 8(x - 2)

= (x - 2)(x - 8)

c) x² - 2x - 8

= x² - 4x + 2x - 8

= (x² - 4x) + (2x - 8)

= x(x - 4) + 2(x - 4)

= (x - 4)(x + 2)

d) 3x² - 7x + 2

= 3x² - x - 6x + 2

= (3x² - x) - (6x - 2)

= x(3x - 1) - 2(3x - 1)

= (3x - 1)(x - 2)