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(x^2-6x+8)(x^2-8x+15)+1
=(x^2-4x-2x+8)(x^2-5x-3x+15)+1
=(x(x-4)-2(x-4))(x(x-5)-3(x-5))+1
=(x-4)(x-2)(x-5)(x-3)+1
=(x-2)(x-5)(x-3)(x-4)+1
=(x^2-7x+10)(x^2-7x+12)+1
Gọi a=x^2-7x+11, ta có
(a-1)(a+1)+1
= a2 - 1 + 1
= a2
= (x2 - 7x + 11)2
a ) \(x^3+3x^2-3x+1\)
\(=x^3-3x+3x^2-1\)
\(=\left(x-1\right)^3\)
Mình ko thêm bớt hạng tử nhé.
\(8x^3-3x+6x^2-1\)
\(=\left(8x^3-1\right)+\left(6x^2-3x\right)\)
\(=\left(2x-1\right)\left(4x^2+2x+1\right)+3x\left(2x-1\right)\)
\(=\left(2x-1\right)\left[\left(4x^2+2x+1\right)+3x\right]\)
\(=\left(2x-1\right)\left(4x^2+5x+1\right)\)
\(=\left(2x-1\right)\left[4x\left(x+1\right)+\left(x+1\right)\right]\)
\(=\left(2x-1\right)\left(x+1\right)\left(4x+1\right)\)
\(8x^3-3x+6x^2-1=\left(8x^3-12x^2+6x-1\right)+\left(18x^2-9x\right)\)
\(=\left(\left(2x\right)^3-3\cdot\left(2x\right)^2\cdot1+3\cdot2x\cdot1^2-1^3\right)+\left(18x^2-9x\right)\)
\(=\left(2x-1\right)^3+9x\left(2x-1\right)=\left(2x-1\right)\left(\left(2x-1\right)^2+9x\right)\)
\(=\left(2x-1\right)\left(4x^2-4x+1+9x\right)=\left(2x-1\right)\left(4x^2+5x+1\right)\)
Mình mới lớp 7 nên chỉ giải được 1 bài thôi!
\(3x^2-7x+2=3x^2-\left(6x+1x\right)+2=3x^2-6x-1x+2\)
\(3x\left(x-2\right)-1\left(x-2\right)=\left(x-2\right)\left(3x-1\right)=3\left(x-2\right)\left(x-\frac{1}{3}\right)\)
\(a.3x^2-12xy=3x\left(x-4y\right)\)
\(b.x^2+7x-2\left(x+7\right)=x\left(x+7\right)-2\left(x+7\right)=\left(x-2\right)\left(x+7\right)\)
\(c.8x^3-8x^2+2x=2x\left(4x^2-4+1\right)=2x\left(2x-1\right)^2\)
\(d.x^2-y^2+12y-36=x^2-\left(y-6\right)^2=\left(x-y-6\right)\left(x-y+6\right)\)
Bài làm
a) 3x2 - 12xy
= 3x( x - 4y )
b) x2 + 7x - 2( x + 7 )
= x( x + 7 ) - 2( x + 7 )
= ( x + 7 )( x - 2 )
c) 8x3 - 8x2 + 2x
= 2x( 4x2 - 4x + 1 )
= 2x( 2x - 1 )2
d) x2 - y2 + 12y - 36
= x2 - ( y2 - 12y + 36 )
= x2 - ( y2 - 2.y.6 + 62 )
= x2 - ( y - 6 )2
= ( x - y + 6 )( x + y - 6 )
# Học tốt #
a) -4x2 + 8x - 4
= - (4x2 - 8x + 4)
= - (2x - 2)2
b) -x52 + 10 x - 5
= - 5(x2 - 2x + 1)
= - 5(x - 1)2
a)\(=\left(x-2\right)\left(5x-3x^2\right)\)
\(=x\left(x-2\right)\left(5-3x\right)\)
b)\(=\left(4x-x^2-4\right)\left(4x+x^2+4\right)\)
\(=-\left(x^2-4x+4\right)\left(x+2\right)^2\)
=\(-\left(x-2\right)^2\left(x+2\right)^2\)
c)\(\left(=5x^2-5xy\right)+\left(7y-7x\right)\)
\(=-5x\left(y-x\right)+7\left(y-x\right)\)
\(=\left(y-x\right)\left(7-5x\right)\)
d)\(=\left(3x^2-6x\right)-\left(2x-4\right)\)
\(=3x\left(x-2\right)-2\left(x-2\right)\)
\(=\left(x-2\right)\left(3x-2\right)\)
e)\(=[\left(x^2\right)^2+8^2+2.x^2.8]-2.8.x^2\)
\(=\left(x^2+8\right)^2-16x^2\)
\(=\left(x^2+8-4x\right)\left(x^2+8+4x\right)\)
__Chúc bạn hc tốt ......
\(4x^4-8x^3+3x^2-8x+4\)
\(=\left(4x^4-8x^3\right)+\left(3x^2-6x\right)-\left(2x-4\right)\)
\(=4x^3\left(x-2\right)+3x\left(x-2\right)-2\left(x-2\right)\)
\(=\left(x-2\right)\left(4x^3+3x-2\right)\)
\(=x^2\left(8x-3\right)-\left(8x-3\right)=\left(8x-3\right)\left(x^2-1\right)\)