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\(xy-y\sqrt{x}+\sqrt{x}-1\)
\(=y\left(x-\sqrt{x}\right)+\left(\sqrt{x}-1\right)\)
\(=y\sqrt{x}\left(\sqrt{x}-1\right)+\left(\sqrt{x}-1\right)\)
\(\left(\sqrt{x}-1\right)\left(y\sqrt{x}+1\right)\)
xét \(x\ne0\)ta có :
\(M=\)\(^{x^2\cdot\left(x^2+6x+7-\frac{6}{x}+\frac{1}{x^2}\right)}\)
Đặt \(x-\frac{1}{x}=t\Rightarrow t^2=x^2-2+\frac{1}{x^2}\Leftrightarrow t^2+2=x^2+\frac{1}{x^2}\)
Do đó \(M=x^2\cdot\left(t^2+2+6t+7\right)\Leftrightarrow x^2\cdot\left(t^2+6t+9\right)\)
\(\Leftrightarrow M=x^2\cdot\left(t+3\right)^2\)
M=\(x^4+3x^3-x^2+3x^3+9x^2-3x-x^2-3x+1\)
\(=x^2(x^2+3x-1)+3x\left(x^2+3x-1\right)-\left(x^2+3x-1\right)\)
\(=\left(x^2+3x-1\right)^2\)
Ta có: \(P\left(x\right)=x^4+6x^3+7x^2-6x+1\)
\(=x^4+\left(6x^3-2x^2\right)+\left(9x^2-6x+1\right)\)
\(=x^4+2x^2\left(3x-1\right)+\left(3x-1\right)^2\)
\(=\left(x^2+3x-1\right)^2\)
a, \(1-a\sqrt{a}\)
\(=\left[1-\left(\sqrt{a}\right)^3\right]\)
\(=\left(1-\sqrt{a}\right)\left[\left(\sqrt{a}\right)^2+1.\sqrt{a}+1^2\right]\)
\(=\left(1-\sqrt{a}\right)\left(a+\sqrt{a}+1\right)\)
b, \(x-2\sqrt{x-1}\)
\(=\left(x-1\right)-2\sqrt{x-1}+1\)
\(=\left[\left(\sqrt{x-1}\right)-1\right]^2\)
\(\sqrt{x^3}-1=\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right).\)
a, \(x-\sqrt{x}\)= \(\sqrt{x}.\left(\sqrt{x}-1\right)\)
b, 3x+6\(\sqrt{x}\)= \(\sqrt{x}.\left(3\sqrt{x}+6\right)\)
c, x+2\(\sqrt{x}+1\)= \(\left(\sqrt{x}\right)^2+2\sqrt{x}+1=\left(\sqrt{x}+1\right)^2\)
d, \(3x-5\sqrt{x}+2=3x-3\sqrt{x}-2\sqrt{x}+2\)
=\(3\sqrt{x}.\left(\sqrt{x}-1\right)-2.\left(\sqrt{x}-1\right)\)
=\(\left(3\sqrt{x}-2\right).\left(\sqrt{x}-1\right)\)
a, \(5+\sqrt{x}+25-x=\left(5+\sqrt{x}\right)+\left(5+\sqrt{x}\right)\left(5-\sqrt{x}\right)=\left(5+\sqrt{x}\right)\left(1+5-\sqrt{x}\right)=\left(5+\sqrt{x}\left(6-\sqrt{x}\right)\right)\)
b, \(xy-x\sqrt{y}+\sqrt{y}-1=x\sqrt{y}\left(\sqrt{y}-1\right)+\sqrt{y}-1=\left(x\sqrt{y}+1\right)\left(\sqrt{y}-1\right)\)
Bài làm:
Ta có: \(-6x+5\sqrt{x}+1\)
\(=\left(-6x+6\sqrt{x}\right)-\left(\sqrt{x}-1\right)\)
\(=-6\sqrt{x}\left(\sqrt{x}-1\right)-\left(\sqrt{x}-1\right)\)
\(=\left(-6\sqrt{x}-1\right)\left(\sqrt{x}-1\right)\)
\(=\left(6\sqrt{x}+1\right)\left(1-\sqrt{x}\right)\)