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a) x³ -7x +6
= x³ -x²+x²-x-6x+6
= x²(x-1)+x(x-1)-6(x-1)
= (x-1)(x² +x-6)
= (x-1)(x²-2x+3x-6)
=(x-1)(x-2)(x+3)
b) x³ +5x²+8x+4
= x³ +x² +4x²+4x+4x+4
= x²(x+1)+4x(x+1)+4(x+1)
=(x+1)(x²+4x+4)
=(x+1)(x+2)²
c) x³ -9x² +6x+16
= x³ +x²-10x²-6x+16x+16
= (x+1)(x² -10x+16)
=(x+1)(x-8)(x-2)
\(B=x^4+3x^3-x^2+3x^3+9x^2-3x-x^2-3x+1\)
\(=\left(x^2+3x-1\right)^2\)
d, 6x2-xy-y2
=6x2-3xy+2xy-y2
=3x(2x-y)-y(2x-y)
=(2x-y)(3x-y)
\(3x^4-48\)
\(=\left(3x^4-6x^3\right)+\left(6x^3-12x^2\right)+\left(12x^2-24x\right)+\left(24x-48\right)\)
\(=3x^3\left(x-2\right)+6x^2\left(x-2\right)+12x\left(x-2\right)+24\left(x-2\right)\)
\(=\left(x-2\right)\left[\left(3x^3+6x^2\right)+\left(12x+24\right)\right]\)
\(=\left(x-2\right)\left[3x^2\left(x+2\right)+12\left(x+2\right)\right]\)
\(=\left(x-2\right)\left(x+2\right)\left(3x^2+12\right)\)
\(x^4-8x\)
\(=x\left(x^3-8\right)\)
\(=x\left[\left(x^3-2x^2\right)+\left(2x^2-4x\right)+\left(4x-8\right)\right]\)
\(=x\left[x^2\left(x-2\right)+2x\left(x-2\right)+4\left(x-2\right)\right]\)
\(=x\left(x-2\right)\left(x^2+2x+4\right)\)
1) 3x^2 +7x-6
=3x2-2x+9x-6
=x.(3x-2)+3.(3x-2)
=(3x-2)(x+3)
2)6x^213x+6
đề khùng
3)8x^2+5x+3
8x2-3x+8x+3
Đề khùng
\(a.x^3+3x^2+4x+2\)
\(=x^3+x^2+2x^2+2x+2\)
\(=x^2\left(x+1\right)+2x\left(x+1\right)+2\left(x+1\right)\)
\(=\left(x+1\right)\left(x^2+2x+2\right)\)
\(b.6x^4-x^3-7x^2+x+1\)
\(=6x^4-6x^3+5x^3-5x^2-2x^2+2x-x+1\)
\(=6x^3\left(x-1\right)+5x^2\left(x-1\right)-2x\left(x-1\right)-\left(x-1\right)\)
\(=\left(x-1\right)\left(6x^3+5x^2-2x-1\right)\)
\(=\left(x-1\right)\left(6x^3+6x^2-x^2-x-x-1\right)\)
\(=\left(x-1\right)\left[6x^2\left(x+1\right)-x\left(x+1\right)-\left(x+1\right)\right]\)
\(=\left(x-1\right)\left(x+1\right)\left(6x^2-x-1\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(6x^2-3x+2x-1\right)\)
\(=\left(x-1\right)\left(x+1\right)\left[3x\left(2x-1\right)+\left(2x-1\right)\right]\)
\(=\left(x-1\right)\left(x+1\right)\left(2x-1\right)\left(3x+1\right)\)
k giùm cái cho đỡ buồn!
5x^2 + 5xy - x - y
=5x.(x+y)-(x+y)
=(x+y)(5x-1)
7x - 6x^2 - 2
=-6x2+3x+4x-2
=-3x.(2x-1)+2.(2x-1)
=(2x-1)(2-3x)
a) x³ -7x +6
= x³ -x²+x²-x-6x+6
= x²(x-1)+x(x-1)-6(x-1)
= (x-1)(x² +x-6)
= (x-1)(x²-2x+3x-6)
=(x-1)(x-2)(x+3)
b) x³ +5x²+8x+4
= x³ +x² +4x²+4x+4x+4
= x²(x+1)+4x(x+1)+4(x+1)
=(x+1)(x²+4x+4)
=(x+1)(x+2)²
c) x³ -9x² +6x+16
= x³ +x²-10x²-6x+16x+16
= (x+1)(x² -10x+16)
=(x+1)(x-8)(x-2)