Question

Phân tich đa thức thành nhân tử:

a) x³ - 2x - 4

b) x² + 4x + 3

c) 16x - 5x² -3

d) 2x² + 7x +5

e) 2x² +3x - 5

Answer 1

a) x³ - 2x -4=x³ - 2x² + 2x² - 4x +2x -4

=x²(x-2) + 2x(x-2)+2(x-2)

=(x-2)(x² +2x +2)

Answer 2

b) x² + 4x +3

=x² + 2.x.2 +2² -1

=(x+2)² - 1²

=(x+2+1)(x+2-1)

=(x+3)(x+1)

Answer 3

d, 2x²+7x+5=2x²+2x+5x+5=2x(x+1)+5(x+1)=(2x+5)(x+1)

e, 2x²+3x-5=2x²-2x+5x-5=2x(x-1)+5(x-1)=(2x+5)(x-1)

Answer 4

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