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3x3 - 7x2+17x - 5
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Lời giải:
Ta có:
\(3x^3-6x^2y+3xy^2-3x^2=3x(x^2-2xy+y^2-x)\)
7x2+15x-5=0
7*(x2+2.5x-5/7)=0
x2+2*x*1.25+1,5625-255/112=0
(x+1.25)2-255/112=0
3x3-7x2+17x-5
=3x3-x2-6x2+2x+15x-5
= x2.(3x-1)-2x.(3x-1)+5.(3x-1)
= (3x-1)(x2-2x+5)
Ta có : \(3x^3-7x^2+17x-5\)
\(=\left(3x^3-x^2\right)-\left(6x^2-2x\right)+\left(15x-5\right)\)
\(=x^2\left(3x-1\right)-2x\left(3x-1\right)+5\left(3x-1\right)\)
\(=\left(3x-1\right)\left(x^2-2x+5\right)\)
\(a,=3\left(x-5\right)-x\left(x-5\right)=\left(3-x\right)\left(x-5\right)\\ b,=7\left(x^2-2xy+y^2\right)=7\left(x-y\right)^2\\ c,=\left(x^2+y^2-2xy\right)\left(x^2+y^2+2xy\right)=\left(x-y\right)^2\left(x+y\right)^2\\ d,=\left(y^2-6y+9\right)-25x^2=\left(y-3\right)^2-25x^2=\left(y-5x-3\right)\left(y+5x-3\right)\)
\(3x^3-7x^2+17x-5\)
\(=3x^3-x^2-6x^2+2x+15x-5\)
\(=x^2\left(3x-1\right)-2x\left(3x-1\right)+5\left(3x-1\right)\)
\(=\left(3x-1\right)\left(x^2-2x+5\right)\)
3x^3-7x^2+17x-5
= (3x^3-x^2)-(6x^2-2x)+(15x-5)
= (3x-1).(x^2-6x+15)
Tk mk nha
Lời giải:
$2x^2-17x+19=2(x^2-8,5x+4,25^2)-\frac{137}{8}$
$=2(x-4,25)^2-\frac{137}{8}=2[(x-\frac{17}{4})^2-\frac{137}{16}]$
$=2(x-\frac{17+\sqrt{137}}{4})(x-\frac{17-\sqrt{137}}{4})$
\(3x^3-7x^2+17x-5.\)
\(=3x^3-x^2-6x^2+2x-15x+5\)
\(=\left(3x^3-x^2\right)-\left(6x^2-2x\right)-\left(15x-5\right)\)
\(=x^2\left(3x-1\right)-2x\left(3x-1\right)-5\left(3x-1\right)\)
\(=\left(3x-1\right)\left(x^2-2x-5\right)\)
\(3x^3-7x^2+17x-5\)
\(=3x^3-6x^2-x^2+15x+2x-5\)
\(=\left(-6x^2+2x\right)+\left(3x^3+15x\right)-\left(x^2+5\right)\)
\(=-2x\left(3x-1\right)+3x\left(x^2+5\right)-\left(x^2+5\right)\)
\(=-2x\left(3x-1\right)+\left(x^2+5\right)\left(3x-1\right)\)
\(=\left(3x-1\right)\left(-2x+x^2+5\right)\)