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\(6x^2+xy-7x-2y^2+7y-5=-\left(y-2x-1\right)\left(2y+3x-5\right)\)
Trả lời:
\(6x^2+xy-7x-2y^2+7y-5=-\left(y-2x-1\right)\left(2y+3x-5\right)\)
Hok_tốt nha
a,\(x^2+2xy+7x+7y+y^2+10=\left(x^2+2xy+y^2\right)+7\left(x+y\right)+10\)
\(=\left(x+y\right)^2+2\left(x+y\right)+5\left(x+y\right)+10\)
\(=\left(x+y\right)\left(x+y+2\right)+5\left(x+y+2\right)\)
\(=\left(x+y+2\right)\left(x+y+5\right)\)
b,\(x^2y+xy^2+x+y=2010\Rightarrow xy\left(x+y\right)+x+y=2010\)
\(\Rightarrow12\left(x+y\right)=2010\Rightarrow x+y=167,5\)
Ta có:\(x^2+y^2=x^2+2xy+y^2-2xy=\left(x+y\right)^2-2xy=\left(167,5\right)^2-2.11=28034,25\)
b)\(x^2y+xy^2-x-y\)
\(=xy\left(x+y\right)-\left(x+y\right)\)
\(=\left(xy-1\right)\left(x+y\right)\)
1/ \(2x^2+5xy+y^2=2\left(x^2+2x.\frac{5y}{4}+\frac{25y^2}{16}-\frac{17y^2}{16}\right)\)
\(=2\left[\left(x+\frac{5y}{4}\right)^2-\left(\frac{\sqrt{17}y}{4}\right)^2\right]=2\left(x+\frac{5-\sqrt{17}}{4}y\right)\left(x+\frac{5+\sqrt{17}}{4}y\right)\)
2/ \(x^2-3xy-2y^2=x^2-2x.\frac{3y}{2}+\frac{9y^2}{4}-\frac{17y^2}{4}\)
\(=\left(x-\frac{3y}{2}\right)^2-\left(\frac{\sqrt{17}y}{2}\right)^2=\left(x+\frac{-3-\sqrt{17}}{2}y\right)\left(x+\frac{-3+\sqrt{17}}{2}y\right)\)
3/ \(6x^2+xy-7x-2y^2+7y-5\)
\(=6x^2+4xy-10x-3xy-2y^2+5y+3x+2y-5\)
\(=2x\left(3x+2y-5\right)-y\left(3x+2y-5\right)+3x+2y-5\)
\(=\left(3x+2y-5\right)\left(2x-y+1\right)\)
4/ \(6a^2-ab-2b^2+a+4b-2\)
\(=6a^2-4ab+4a+3ab-2b^2+2b-3a+2b-2\)
\(=2a\left(3a-2b+2\right)+b\left(3a-2b+2\right)-\left(3a-2b+2\right)\)
\(=\left(3a-2b+2\right)\left(2a+b-1\right)\)
\(b,x^2+6x+5=x^2+x+5x+5=x\left(x+1\right)+5\left(x+1\right)=\left(x+1\right)\left(x+5\right)\)
\(c,x^2-7x+10=x^2-2x-5x+10=x\left(x-2\right)-5\left(x-2\right)=\left(x-2\right)\left(x-5\right)\)