phân tích đa thức thành nhân tử x\(\sqrt{x}\) - 3x + 4\(\sqrt{x}\) -2 ( x > 0 )
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\(x\sqrt{x}-3x+4\sqrt{x}-2=x\sqrt{x}-x-2x+2\sqrt{x}+2\sqrt{x}-2\)
\(=x\left(\sqrt{x}-1\right)-2\sqrt{x}\left(\sqrt{x}-1\right)+2\left(\sqrt{x}-1\right)\)
\(=\left(\sqrt{x}-1\right)\left(x-2\sqrt{x}+2\right)\)
a) \(x^3+9x^2+27x+27=\left(x+3\right)^3\)
b) \(3\sqrt{3x^3}+18x^2+12\sqrt{3x}+8=\left(\sqrt{3x}+2\right)^3\)
c) \(\dfrac{1}{4}-x^2=\left(\dfrac{1}{2}-x\right)\left(\dfrac{1}{2}+x\right)\)
a ) \(x+\sqrt{x}=\left(\sqrt{x}\right)^2+\sqrt{x}=\sqrt{x}\left(\sqrt{x}+1\right)\)
b ) \(x-4\sqrt{x}+3=\left(\sqrt{x}\right)^2-2.\sqrt{x}.2+2^2-1=\left(\sqrt{x}-2\right)^2-1\)
\(=\left(\sqrt{x}-2\right)^2-1^2=\left(\sqrt{x}-2+1\right)\left(\sqrt{x}-2-1\right)=\left(\sqrt{x}-1\right)\left(\sqrt{x}-3\right)\)
\(x+\sqrt{x}=\left(\sqrt{x}\right)^2+\sqrt{x}=\sqrt{x}.\left(\sqrt{x}+1\right)\)
\(x-4\sqrt{x}+3=\left[\left(\sqrt{x}\right)^2-2.\sqrt{x}.2+2^2\right]-1^2=\left(\sqrt{x}-2\right)^2-1^2\)
\(=\left(\sqrt{x}-2-1\right)\left(\sqrt{x}-2+1\right)\)
\(=\left(\sqrt{x}-3\right)\left(\sqrt{x}-1\right)\)
a/ \(x^5+x+1=\left(x^5+x^4+x^3\right)+\left(-x^4-x^3-x^2\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^3-x^2+1\right)\)
c/ \(x\sqrt{x}-3x+4\sqrt{x}-2=\left(x\sqrt{x}-x\right)+\left(-2x+2\sqrt{x}\right)+\left(2\sqrt{x}-2\right)\)
\(=\left(\sqrt{x}-1\right)\left(x-2\sqrt{x}+2\right)\)
1) \(x\sqrt{x}+y\sqrt{y}=\left(\sqrt{x}+\sqrt{y}\right)\left(x-\sqrt{xy}+y\right)\)
2) \(x-3=\left(\sqrt{x}-\sqrt{3}\right)\left(\sqrt{x}+\sqrt{3}\right)\)
3) \(a+b=a-\left(-b\right)=\left(\sqrt{a}-\sqrt{-b}\right)\left(\sqrt{a}+\sqrt{-b}\right)\)
p/s: chúc bạn học tốt
Lời giải:
$x\sqrt{x}-3x+4\sqrt{x}-2=(x\sqrt{x}-x)-(2x-2\sqrt{x})+(2\sqrt{x}-2)$
$=x(\sqrt{x}-1)+2\sqrt{x}(\sqrt{x}-1)+2(\sqrt{x}-1)$
$=(\sqrt{x}-1)(x+2\sqrt{x}+2)$