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B= 2x^2+2x+3x+3
= 2x(x+1)+3(x+1)
=(x+1)( 2x+3)
C=3x^2-6x-x+2
=3x(x-2)-(x-2)
=(x-2)(3x-1)
= x^4 + x^3 + 4x^3 + 4x^2 - 11x^2 - 11x -30x - 3
= x^3 ( x + 1) + 4x^2 ( x + 1)- 11x( x + 1) - 30 ( x+ 1)
= ( x + 1)(x^3 + 4x^2 - 11x - 30)
= ( x + 1) [ x^3 - 3x^2 + 7x^2 - 21x + 10x - 30]
= ( x + 1) [ x^2 ( x - 3) + 7x(x - 3) + 10 ( x- 3) ]
= ( x + 1 ) (x - 3 )(x^2 + 7x + 10)
= ( x + 1)(x - 3) [ x^2 + 2x + 5x + 10)
= ( x+ 1)(x-3) [ x(x+2) + 5(x+2) ]
=(x + 1)(x-3)(x+2)(x+5)
a,\(3x^2-30x+75=3\left(x^2-10x+25\right)=3\left(x-5\right)^2\)
b, \(xy-x^2-x+y=x\left(y-x\right)+\left(y-x\right)=\left(y-x\right)\left(x+1\right)\)
c,\(x^2-7x-8=x^2-8x+x-8=x\left(x-8\right)+\left(x-8\right)=\left(x-8\right)\left(x+1\right)\)
a) 3x2 - 30x + 75 = 3.(x2 - 10x + 25) = 3.(x2 - 2.5.x + 52) = 3.(x-5)2
b) xy - x2 - x + y = x.(y-x) + (y-x) = (y-x).(x+1)
c) x2 - 7x - 8 = x2 + x - 8x - 8 = x.(x+1) - 8.(x+1) = (x+1).(x-8)
Ta có :
\(x^6+3x^5-2x^4+7x^3-2x^2+3x+1\)
\(=x^6-x^5+x^4+4x^5-4x^4+4x^3+x^4-x^3+x^2+4x^3-4x^2+4x+x^2-x+1\)
\(=x^4\left(x^2-x+1\right)+4x^3\left(x^2-x+1\right)+x^2\left(x^2-x+1\right)+4x\left(x^2-x+1\right)+\left(x^2-x+1\right)\)
\(=\left(x^2-x+1\right)\left(x^4+4x^3+x^2+4x+1\right)\)
Lời giải:
a.
$2x^4-7x^3-2x^2+13x+6$
$=(2x^4-4x^3)-(3x^3-6x^2)-(8x^2-16x)-(3x-6)$
$=2x^3(x-2)-3x^2(x-2)-8x(x-2)-3(x-2)$
$=(x-2)(2x^3-3x^2-8x-3)$
$=(x-2)[2x^2(x-3)+3x(x-3)+(x-3)]$
$=(x-2)(x-3)(2x^2+3x+1)$
$=(x-2)(x-3)[2x(x+1)+(x+1)]$
$=(x-2)(x-3)(x+1)(2x+1)$
b.
$(x^2+1)-x(a^2+1)$
Đa thức này không phân tích được thành nhân tử bạn nhé.
Ta có : \(M=\left(x^2+3x+2\right)\left(x^2+7x+12\right)+1=\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)+1\)
\(=\left[\left(x+1\right)\left(x+4\right)\right].\left[\left(x+2\right)\left(x+3\right)\right]+1=\left(x^2+5x+4\right)\left(x^2+5x+6\right)+1\)
Đặt \(t=x^2+5x+5\) \(\Rightarrow M=\left(t-1\right)\left(t+1\right)+1=t^2-1+1=t^2\)
Vậy \(M=\left(x^2+5x+5\right)^2\)
\(5x^2-7x+2\)
\(=5x^2-5x-2x+2\)
\(=5x\left(x-1\right)-2\left(x-1\right)\)
\(=\left(x-1\right)\left(5x-2\right)\)
\(5x^2-7x+2\)
\(=5x^2-5x-2x+2\)
\(=5x\left(x-1\right)-2\left(x-1\right)\)
\(=\left(5x-2\right)\left(x-1\right)\)