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= \(8x^4-8x^3+6x^3-6x^2+3x^2-3x+x-1\)
\(=\left(x-1\right)\left(8x^3+6x^2+3x+1\right)\)
\(=\left(x-1\right)\left(8x^3+4x^2+2x^2+x+2x+1\right)\)
\(=\left(x-1\right)\left(2x+1\right)\left(4x^2+x+1\right)\)
x8+x+1=x8-x5+x5-x2+x2+x+1
=x5.(x3-1)+x2.(x3-1)+(x2+x+1)
=x5.(x-1)(x2+x+1)+x2.(x-1)(x2+x+1)+(x2+x+1)
=(x2+x+1)(x6-x5+x3-x2+1)
= x^5 - x^3 - x² - x^4 + x² + x + x^3 - x - 1
= x²( x^3 - x - 1 ) - x( x^3 - x - 1 ) + ( x^3 - x - 1 )
= ( x² - x + 1)( x^3 - x - 1 )
b,\(\sqrt{16\left(x+1\right)}-\sqrt{9\left(x+1\right)}+\sqrt{4\left(x+1\right)}-16\sqrt{x+1}=0\) (dk \(x\ge-1\)
\(\Leftrightarrow\sqrt{x+1}\left(4-3+2-16\right)=0\)
\(\Leftrightarrow\sqrt{x+1}.-13=0\)
\(\Leftrightarrow x=-1\)
Câu a : \(\sqrt{xy}-x=\sqrt{x}\left(\sqrt{y}-\sqrt{x}\right)\)
Câu b : \(x+y-2\sqrt{xy}=\left(\sqrt{x}-\sqrt{y}\right)^2=\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}-\sqrt{y}\right)\)
Câu c : \(\sqrt{xy}+2\sqrt{x}-3\sqrt{y}-6=\sqrt{x}\left(\sqrt{y}+2\right)-3\left(\sqrt{y}+2\right)=\left(\sqrt{x}-3\right)\left(\sqrt{y}+2\right)\)
Câu d : \(x\sqrt{y}-y\sqrt{x}=\sqrt{xy}\left(\sqrt{x}-\sqrt{y}\right)\)
a,\(a\sqrt{b}-b\sqrt{a}\)= \(\sqrt{ab}\left(\sqrt{a}+\sqrt{b}\right)\)
b,\(x\sqrt{x}+\sqrt{x}-x-1\)
=\(\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right)\)-\(\sqrt{x}\left(\sqrt{x}-1\right)\)
=\(\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1-\sqrt{x}\right)\)
=\(\left(\sqrt{x}-1\right)\left(x+1\right)\)
c,\(\sqrt{ab}+2\sqrt{a}+3\sqrt{b}+6\)=\(\sqrt{a}\left(\sqrt{b}+2\right)\)+\(3\left(\sqrt{b}+2\right)\)
=\(\left(\sqrt{b}+2\right)\left(3+\sqrt{a}\right)\)
d,\(\sqrt{ax}-\sqrt{by}+\sqrt{bx}-\sqrt{ay}\)
=\(\sqrt{a}\left(\sqrt{x}-\sqrt{y}\right)+\sqrt{b}\left(\sqrt{x}-\sqrt{y}\right)\)
=\(\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{a}+\sqrt{b}\right)\)
a, f(x)= (x^5-x^4)-(4x^4-4x^3)+(5x^3-5x^2)-(4x^2-4x)+(4x-4)
=x^4(x-1)-4x^3(x-1)+5x^2(x-1)-4x(x-1)+4(x-1)
=(x^4-4x^3+5x^2-4x+4)(x-1)
=[(x^4-2x^3)-(2x^3-4x^2)+(x^2-2x)-(2x-4)](x-1)
=(x^3-2x^2+x-2)(x-2)(x-1)
=(x^2+1)(x-2)^2(x-1)