Question

bài 1; phân tích đa thức sau thành nhân tử

a, x mũ 2 + 5x + 6

a, x mũ 2 + 3x - 4

a, x mũ 2 - 10x + 16

a, 6x mũ 2 - 7x - 20

 

Answer 1

a) = x² + 2x + 3x + 6 = x( x + 2 ) + 3( x + 2 ) = ( x + 2 )( x + 3 )

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

c) = ( x² - 10x + 25 ) - 9 = ( x - 5 )² - 3² = ( x - 8 )( x - 2 )

d) = 6x² - 15x + 8x - 20 = 3x( 2x - 5 ) + 4( 2x - 5 ) = ( 2x - 5 )( 3x + 4 )

Answer 2

a) x² + 5x + 6 = x² + 2x + 3x + 6 

= x(x + 2) + 3(x + 2) = (x + 3)(x + 2)

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

c) x² - 10x + 16 = x² - 2x - 8x + 16 = x(x - 2) - 8(x - 2) = (x - 8)(x - 2)

d) 6x² - 7x - 20 = 6x² + 8x - 15x - 20 = 2x(3x + 4) - 5(3x + 4) = (2x - 5)(3x + 4) 

Answer 3

a.\(x^2+5x+6=x^2+2x+3x+6=x\left(x+2\right)+3\left(x+2\right)=\left(x+3\right)\left(x+2\right)\)

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

c.\(x^2-10x+16=x^2-8x-2x+16=x\left(x-8\right)-2\left(x-8\right)=\left(x-2\right)\left(x-8\right)\)

d.\(6x^2-7x-20=6x^2-12x+5x-20=6x\left(x-4\right)+5\left(x-4\right)=\left(6x+5\right)\left(x-4\right)\)

Answer 4

Trả lời:

a, x² + 5x + 6 = x² + 2x + 3x + 6 = x ( x + 2 ) + 3 ( x + 2 ) = ( x + 2 )( x + 3 )

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

c, x² - 10x + 16 = x² - 8x - 2x + 16 = x ( x - 8 ) - 2 ( x - 8 ) = ( x - 8 )( x - 2 )

d, 6x² - 7x - 20 = 6x² - 15x + 8x - 20 = 3x ( 2x - 5 ) + 4 ( 2x - 5 ) = ( 2x - 5 )( 3x + 4 )