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\(=\left|\sqrt{11}-3\right|-\left|\sqrt{11}-4\right|=\sqrt{11}-3+\sqrt{11}-4=-7+2\sqrt{11}\)
\(\sqrt{3-\sqrt{29-12\sqrt{5}}}=\sqrt{3-\sqrt{\left(2\sqrt{5}-3\right)^2}}=\sqrt{3-2\sqrt{5}+3}=\sqrt{6-2\sqrt{5}}=\sqrt{\left(\sqrt{5}-1\right)^2}=\sqrt{5}-1\)
\(=\sqrt{3-\sqrt{\left(2\sqrt{5}-3\right)^2}}=\sqrt{3-2\sqrt{5}+3}=\sqrt{9-2\sqrt{5}}\)
\(\dfrac{5\sqrt{2}-\sqrt{8}+\sqrt{32}}{\sqrt{2}}=\dfrac{5\sqrt{2}-2\sqrt{2}+4\sqrt{2}}{\sqrt{2}}=\dfrac{7\sqrt{2}}{\sqrt{2}}=7\)
`(5sqrt2-sqrt8+sqrt32):sqrt2`
`= \frac{5sqrt2}{sqrt2}-\frac{sqrt8}{sqrt2}+\frac{sqrt32}{sqrt2}`
`= 5-sqrt4+sqrt16`
`= 5-2+4`
`= 7`
\(=\sqrt{4\sqrt{3}+2\left(2-\sqrt{3}\right)}\)
\(=\sqrt{4\sqrt{3}+4-2\sqrt{3}}\)
\(=\sqrt{4+2\sqrt{3}}=\sqrt{3}+1\)
x + 2 x - 3 = x - x + 3 x - 3 = x ( x - 1) + 3( x - 1) = ( x - 1)( x + 3)
a) Với điểu kiện x ≥ 0; x ≠ 1 ta có:
\(\dfrac{4}{\sqrt{7}+\sqrt{3}}+\dfrac{4}{\sqrt{7}-\sqrt{3}}\\ =\dfrac{4\left(\sqrt{7}-\sqrt{3}\right)}{\left(\sqrt{7}+\sqrt{3}\right)\left(\sqrt{7}-\sqrt{3}\right)}+\dfrac{4\left(\sqrt{7}+\sqrt{3}\right)}{\left(\sqrt{7}+\sqrt{3}\right)\left(\sqrt{7}-\sqrt{3}\right)}\\ =\dfrac{4\left(\sqrt{7}-\sqrt{3}\right)}{7-3}+\dfrac{4\left(\sqrt{7}+\sqrt{3}\right)}{7-3}\\ =\dfrac{4\left(\sqrt{7}-\sqrt{3}\right)}{4}+\dfrac{4\left(\sqrt{7}+\sqrt{3}\right)}{4}\\ =\sqrt{7}-\sqrt{3}+\sqrt{7}+\sqrt{3}\\ =2\sqrt{7}\)
@seven
\(\dfrac{2}{\sqrt{3}-1}-\dfrac{4}{1+\sqrt{5}}-\left(\sqrt{3}-\sqrt{5}\right)=\dfrac{2\left(\sqrt{3}+1\right)}{3-1}-\dfrac{4\left(1-\sqrt{5}\right)}{1-5}-\sqrt{3}+\sqrt{5}=\sqrt{3}+1+1-\sqrt{5}-\sqrt{3}+\sqrt{5}=2\)