Phân tích đa thức thành nhân tử:
5x(x-1)-x-1
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\(3x\left(x+1\right)^2-5x^2\left(x+1\right)+7\left(x+1\right)\)
\(=\left(x+1\right)\left(3x^2+3x-5x^2+7\right)\)
\(=\left(x+1\right)\left(-2x^2+3x+7\right)\)
\(x^3+5x^2+5x+1\)
\(=\left(x+1\right)\left(x^2+x+1\right)+5x\left(x+1\right)\)
\(=\left(x+1\right)\left(x^2+6x+1\right)\)
\(=x^2-5x+\dfrac{25}{4}-\dfrac{29}{4}\)
\(=\left(x-\dfrac{5}{2}\right)^2-\dfrac{29}{4}\)
\(=\left(x-\dfrac{5}{2}-\dfrac{\sqrt{29}}{2}\right)\left(x-\dfrac{5}{2}+\dfrac{\sqrt{29}}{2}\right)\)
\(4x\left(x+1\right)^2-5x^2\left(x+1\right)-4\left(x+1\right) =\left(x+1\right)\left[4x\left(x+1\right)-5x^2-4\right]=\left(x+1\right)\left(4x^2+4x-5x^2-4\right)=\left(x+1\right)\left(-x^2+4x-4\right)=-\left(x+1\right)\left(x-2\right)^2\)
\(4x\left(x+1\right)^2-5x^2\left(x+1\right)-4\left(x+1\right)\)
\(=4x\left(x^2+2x+1\right)-5x^2\left(x+1\right)-4\left(x+1\right)\)
\(=4x^3+8x^2+4x-5x^3-5x-4x-4\)
\(=-x^3+8x^2-5x-4\)
a) x2-x=x(x-1)
b) 3x-3y = 3(x-y)
c)3xy2+6xyz=3xy(y+2z)
d) 5x-20y=5(x-4y)
g) 5x(x-1)-(1-x)=5x(x-1)+(x-1)=(5x+1)(x-1)
a, \(x^2-x=x\left(x-1\right)\)
b, \(3x-3y=3\left(x-y\right)\)
c, \(3xy^2+6xyz=3xy\left(y+2z\right)\)
d, \(5x-20y=5\left(x-4y\right)\)
g, \(5x\left(x-1\right)-\left(1-x\right)=\left(5x+1\right)\left(x-1\right)\)
-Đặt \(t=\left(x^2-x+1\right)\)
\(\left(x^2-x+1\right)^2-5x\left(x^2-x+1\right)+4x^2\)
\(=t^2-5xt+4x^2\)
\(=t^2-4xt-xt+4x^2\)
\(=t\left(t-4x\right)-x\left(t-4x\right)\)
\(=\left(t-4x\right)\left(t-x\right)\)
\(=\left(x^2-x+1-4x\right)\left(x^2-x+1-x\right)\)
\(=\left(x^2-5x+1\right)\left(x^2-2x +1\right)\)
\(=\left(x^2-5x+1\right)\left(x-1\right)^2\)
`#3107.101107`
a)
`A = 2x^2 + 5x^3 + x^2y`
`= x^2 * (2 + 5x + y)`
b)
`5x(x - 1) + 15(x - 1)`
`= (5x + 15)(x - 1)`
`= 5(x + 3)(x - 1)`
5x(x-1)-x-1
\(=5x^2-5x-x-1\)
\(=5x^2-6x-1\)
\(=5\left(x^2-\frac65x-\frac15\right)\)
\(=5\left(x^2-2\cdot x\cdot\frac35+\frac{9}{25}-\frac{14}{25}\right)\)
\(=5\left\lbrack\left(x-\frac35\right)^2-\frac{14}{25}\right\rbrack=5\left(x-\frac35-\frac{\sqrt{14}}{5}\right)\left(x-\frac35+\frac{\sqrt{14}}{5}\right)\)
`5x(x-1)-x-1`
`=5x^2-5x-x-1`
`=5x^2-6x-1`
`=5(x^2-6/5x-1/5)`
`=5[(x^2-6/5x+9/25)-9/25-1/5]`
`=5[(x-3/5)^2-14/15]`
`=5[(x-3/5)^2-(\sqrt{14}/5)^2]`
`=5(x-3/5-\sqrt{14}/5)(x-3/5+\sqrt{14}/5)`