\(\frac{3}{4+\sqrt{9+4\sqrt{5}}}=\frac{3}{4+\sqrt{5+2\sqrt{5}.2+4}}=\frac{3}{4+\sqrt{\left(\sqrt{5}+2\right)^2}}=\frac{3}{4+\sqrt{5}+2}=\frac{3}{6+\sqrt{5}}\)
Rút gọn:
a, A = \(\frac{1}{\sqrt{3}+\sqrt{1}}+\frac{1}{\sqrt{5}+\sqrt{3}}+\frac{1}{\sqrt{7}+\sqrt{5}}+\frac{1}{\sqrt{9}+\sqrt{7}}\)
b, B = \(2\sqrt{40\sqrt{12}}-2\sqrt{\sqrt{75}}-3\sqrt{5\sqrt{48}}\)
c, C = \(\frac{15}{\sqrt{6}+1}+\frac{4}{\sqrt{6}-2}-\frac{12}{3-\sqrt{6}}-\sqrt{6}\)
d, D = \(\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}\) với x ≥ 2
Trục căn thức ở mẫu
1) \(\frac{2}{\sqrt{20}}\)
2) \(\frac{4}{\sqrt{8}}\)
3) \(\frac{2+\sqrt{3}}{\sqrt{2}}\)
4) \(\frac{1}{\sqrt{6}-2}\)
5) \(\frac{1}{\sqrt{2}-\sqrt{3}}\)
6) \(\frac{9a-b}{3\sqrt{a}-\sqrt{b}}\) ( a> 0, b> 0)
7) \(\frac{3\sqrt{2}}{1-\sqrt{2}-\sqrt{3}}\)
8) \(\frac{3\sqrt{3}}{\sqrt{2}+\sqrt{3}+\sqrt{5}}\)
9) \(\frac{\sqrt{2}+\sqrt{3}+\sqrt{6}+\sqrt{8}+4}{\sqrt{2}+\sqrt{3}+\sqrt{4}}\)
Tính
a)\(\frac{\sqrt{15}-\sqrt{5}}{\sqrt{3}-1}-\frac{5-2\sqrt{5}}{2\sqrt{5}-4}\)
b)\(\frac{2\sqrt{8}-\sqrt{12}}{\sqrt{3}-1}-\frac{\sqrt{5}+\sqrt{27}}{\sqrt{30}-\sqrt{2}}\)
c)\(\frac{2}{\sqrt{3}-1}-\frac{2}{\sqrt{3}+1}\)
1,Rút gọn
D=\(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)
2,Rút gọn
M=\(\left(\frac{1}{x-4}-\frac{1}{x+4\sqrt{x}+4}\right)\frac{x+2\sqrt{x}}{\sqrt{x}}\)
Với x>0, x\(\ne\)4
3,Rút gọn
N=\(\left(\frac{3\sqrt{x}+6}{x-4}+\frac{\sqrt{x}}{\sqrt{x}-2}\right):\frac{x-9}{\sqrt{x}-3}\)
Với x>0, x\(\ne\)4, x\(\ne\)9
Giúp mk với, mk đang cần gấp, cảm ơn trước nha
Bài 1: khử mẫu của biểu thức lấy căn
1) \(\sqrt{\frac{2}{3-\sqrt{5}}}\)
2) \(\sqrt{\frac{a-4}{2\left(\sqrt{a}-2\right)}}\) (a > 4)
3) \(\sqrt{\frac{1}{a\left(1-\sqrt{3}\right)}}\)
4) \(\sqrt{\frac{a}{4-2\sqrt{3}}}\)
Giải 5 câu sau:
1. \(\dfrac{\sqrt{5}+2}{\sqrt{5}-2}\)
2. \(\dfrac{5\sqrt{2}-2\sqrt{5}}{\sqrt{2}-\sqrt{5}}\)
3. \(\dfrac{\sqrt{20}-3\sqrt{10}}{3-\sqrt{5}}\)
4. \(\dfrac{6-2\sqrt{5}}{3+\sqrt{5}}\)
5. \(\dfrac{9+4\sqrt{5}}{\sqrt{5}+2}\)
Giải phương trình :
a) \(\left(\sqrt{x}-2\right)\left(5-\sqrt{x}\right)=4-x\)
b) \(\frac{\sqrt{x+5}}{\sqrt{x+4}}=\frac{\sqrt{x-2}}{\sqrt{x+3}}\)
c) \(\frac{1}{x+\sqrt{x^2+1}}+\frac{1}{x-\sqrt{x^2+1}}=4\)
Tính:
a/ \(\frac{2}{\sqrt{3}-1}+\frac{3}{\sqrt{3}-2}+\frac{12}{3-\sqrt{3}}\)
b/ \(\frac{1}{\sqrt{3}-\sqrt{2}}-\frac{2}{\sqrt{7}+\sqrt{5}}-\frac{3}{\sqrt{5}-\sqrt{2}}+\frac{4}{\sqrt{7}+\sqrt{3}}\)
c/ \(\frac{\sqrt{14}-\sqrt{17}}{1-\sqrt{2}}\)
d/ \(\frac{3\sqrt{2}-3}{\sqrt{2}-1}\)
e/ \(\frac{5\sqrt{a}-\sqrt{ab}}{\sqrt{b}-5}\)
\(\frac{4+\sqrt{3}}{\sqrt{1}+\sqrt{3}}+\frac{8+\sqrt{15}}{\sqrt{3}+\sqrt{5}}+...+\frac{240+\sqrt{14399}}{\sqrt{119}+\sqrt{121}}\) ai bt giúp mik với thanks so much
