\(Cho\)\(\frac{1}{\sqrt[3]{4-15}}+\sqrt[3]{4-15}\)
\(Tính\)\(A=x^3-3x+2014\)
Tính giá trị biểu thức sau A=\(\frac{1+\sqrt{7}}{\sqrt{2}+\sqrt{4+\sqrt{7}}}+\frac{1-\sqrt{7}}{\sqrt{2}-\sqrt{4-\sqrt{7}}}\)
B=(3x3-x2-1)2014 với \(x=\frac{\sqrt{26+15\sqrt{3}\left(2-\sqrt{3}\right)}}{3}\)
\(\frac{A}{\sqrt{2}}=\frac{1+\sqrt{7}}{2+\sqrt{8+2\sqrt{7}}}+\frac{1-\sqrt{7}}{2-\sqrt{8-2\sqrt{7}}}\)
\(=\frac{1+\sqrt{7}}{2+1+\sqrt{7}}+\frac{1-\sqrt{7}}{2-\sqrt{7}+1}\)
\(=\frac{1+\sqrt{7}}{3+\sqrt{7}}+\frac{1-\sqrt{7}}{3-\sqrt{7}}\)
=\(\frac{\left(1+\sqrt{7}\right)\left(3-\sqrt{7}\right)+\left(1-\sqrt{7}\right)\left(3+\sqrt{7}\right)}{\left(3+\sqrt{7}\right)\left(3-\sqrt{7}\right)}\)
\(=\frac{-8}{2}=-4\)
\(\Rightarrow A=-4\sqrt{2}\)
Cho \(x=\frac{1}{\sqrt[3]{4-\sqrt{15}}}+\sqrt[3]{4-\sqrt{15}}\)
Tính \(y=x^3-3x+1987\)
\(x=\frac{1}{\sqrt[3]{4-\sqrt{15}}}+\sqrt[3]{4-\sqrt{15}}\)
\(\Leftrightarrow x^3=\frac{1}{4-\sqrt{15}}+4-\sqrt{15}+3\sqrt[3]{\sqrt[3]{\frac{1}{4-\sqrt{5}}}.\sqrt[3]{4-\sqrt{5}}}.x\)
\(=4+\sqrt{15}+4-\sqrt{15}+3x=8+3x\)
=>y=3x+8-3x+1987
=1995
Cho A = \(\frac{2x+15\sqrt{x}+18}{x+3\sqrt{x}-18}+\frac{3x+4\sqrt{x}+1}{2x-3\sqrt{x}-5}-\frac{8x-15\sqrt{x}}{2x\sqrt{x}-11x+5\sqrt{x}}\)
Tính A tại \(x=\sqrt[3]{2+\sqrt{5}}+\sqrt[3]{2-\sqrt{5}}\)
Cho x=\(\frac{1}{\sqrt[3]{4-\sqrt{15}}}+\sqrt[3]{4-\sqrt{15}}\). Tính A= \(x^3\)+ 3x + 2006
Các bạn trả lời dùm mình nhak, cần gấp lắm. Bạn nào nhanh mình tick cho :))
\(x=\frac{1}{\sqrt[3]{4-\sqrt{15}}}+\sqrt[3]{4-\sqrt{15}}\)
<=> \(x^3=\frac{1}{4-\sqrt{15}}+3\left(\frac{1}{\sqrt[3]{4-\sqrt{15}}}+\sqrt[3]{4-\sqrt{15}}\right)\left(\frac{1}{\sqrt[3]{4-\sqrt{15}}}.\sqrt[3]{4-\sqrt{15}}\right)\)
\(+4-\sqrt{15}\)
<=> \(x^3=\frac{1}{4-\sqrt{15}}+4-\sqrt{15}+3x\)
<=> \(x^3-3x+2006=\frac{1}{4-\sqrt{15}}+4-\sqrt{15}+2006\)
<=> \(x^3-3x+2006=\frac{4+\sqrt{15}}{16-15}+4-\sqrt{15}+2006\)
<=> \(x^3-3x+2006=2014\)
a) Tính giá trị biểu thức:
N=\(\frac{\sqrt{15-10\sqrt{2}}+\sqrt{13+4\sqrt{10}}-\sqrt{11+2\sqrt{10}}}{2\sqrt{3+2\sqrt{2}}+\sqrt{9-4\sqrt{2}}+\sqrt{12+8\sqrt{2}}}\)
b)Rút gọn biểu thức:
A=\(\frac{x^3-3x+\left(x^2-1\right)\sqrt{x^2-4}-2}{x^3-3x+\left(x^2-1\right)\sqrt{x^2-4}+2}\),trị x>2
Tính
1, a = \(\sqrt[3]{45+26\sqrt{2}}+\sqrt[3]{45-29\sqrt{2}}\)
2, x = \(\sqrt[3]{4+\sqrt{80}-\sqrt[3]{\sqrt{80}-4}}\)
3, \(\left(4+\sqrt{15}\right)\cdot\left(\sqrt{10}-\sqrt{6}\right)\cdot\sqrt{4-\sqrt{15}}\)
4, \(\sqrt{4-\sqrt{7}}-\sqrt{4+\sqrt{7}}\)
5, \(\sqrt{\frac{4-\sqrt{7}}{4+\sqrt{7}}}+\sqrt{\frac{4+\sqrt{7}}{4-\sqrt{7}}}\)
Cho
\(M=\frac{4\left(x+1\right)x^{2015}-2x^{2014}+2x+1}{2x^2+3x}\)
Tính M tại \(x=\sqrt{\frac{1}{2\sqrt{3}-2}-\frac{3}{2\left(\sqrt{3}+1\right)}}\)
Cho x=\(\dfrac{1}{\sqrt[3]{4-\sqrt{15}}}+\sqrt[3]{4-\sqrt{15}}\)
Tính P=x3-3x+2006
@DƯƠNG PHAN KHÁNH DƯƠNG
@Akai Haruma
Giúp e vs
Tính:
\(\frac{2\sqrt{3}-1}{\sqrt{15}}-\frac{2-\sqrt{5}}{\sqrt{3}}-\frac{4\sqrt{15}-10\sqrt{3}}{15}\)