Question

Phân tích đa thức thành nhân tử

a.\(8x^2+10x\)

b.\(4x^2-8x+4\)

c.\(3x^2-3xy-5x+5y\)

d.\(x^2+4x-45\)

Answer 1

a, 8x²+10x =2x.(4x+5)

b, 4x²-8x+4 =4.(x² -2x+1)=4.(x-1)²

c, 3x² -3xy -5x +5y =(3x²-5x) - (3xy-5y) = x.(3x-5)- y.(3x-5)= (x-y).(3x-5)

d, x²+ 4x- 45=x²+ 9x- 5x- 45= x.(x+9)- 5.(x+9)=(x-5).(x+9)

Answer 2

a , 8 x ² + 10 x

= 2 x ( 4 x + 5 )

b , 4 x ² - 8 x + 4

= ( 2x ) ² - 2 . 2 x . 2 + 2 ²

= ( 2x + 2 ) ²

c ) 3 x ² - 3 x y - 5 x + 5 y

= 3 x ( x - y ) - 5 ( x - y )

= ( 3x - 5 ) ( x - y )

d ) x ² + 4x - 45

= x ² + 2 x . 2 + 4 - 49

= ( x + 2 ) ² - 49

= ( x + 2 ) ² - 7 ²

= ( x + 2 - 7 ) ( x + 2 + 7)

= ( x - 5 ) ( x + 9 )