\(A=\sqrt{7-2\sqrt{10}}+\sqrt{7+2\sqrt{10}}\)
\(A^2=\left(7+2\sqrt{10}+7-2\sqrt{10}\right)+2\sqrt{\left(7-2\sqrt{10}\right)\left(7+2\sqrt{10}\right)}\)
\(=14+2\sqrt{49-40}=14+6=20\)
Khi đó:\(A=\sqrt{20}\)
Các câu còn lại bạn làm nốt nhé
Các câu hỏi tương tự
thực hiện phép tính:
a)\(\left(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}\right).\frac{1}{\sqrt{6}}\)
b)\(\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right):\frac{1}{\sqrt{7}-\sqrt{5}}\)
c)\(\frac{\sqrt{5-2\sqrt{6}}+\sqrt{8-2\sqrt{15}}}{\sqrt{7+2\sqrt{10}}}\)
Thực hiện phép tính:a)left(frac{2sqrt{3}-sqrt{6}}{sqrt{8}-2}-frac{sqrt{216}}{3}right).frac{1}{sqrt{6}}b) left(frac{sqrt{14}-sqrt{7}}{1-sqrt{2}}+frac{sqrt{15}-sqrt{5}}{1-sqrt{3}}right):frac{1}{sqrt{7}-sqrt{5}}c) frac{sqrt{5-2sqrt{6}}+sqrt{8-2sqrt{15}}}{sqrt{7+2sqrt{10}}}d) left(sqrt{28}-2sqrt{14}+sqrt{7}right).sqrt{7}+7sqrt{8}
Đọc tiếp
Thực hiện phép tính:
a)\(\left(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}\right).\frac{1}{\sqrt{6}}\)
b) \(\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right):\frac{1}{\sqrt{7}-\sqrt{5}}\)
c) \(\frac{\sqrt{5-2\sqrt{6}}+\sqrt{8-2\sqrt{15}}}{\sqrt{7+2\sqrt{10}}}\)
d) \(\left(\sqrt{28}-2\sqrt{14}+\sqrt{7}\right).\sqrt{7}+7\sqrt{8}\)
Rút gọn các biểu thức sau:
a) \(0,2\sqrt{\left(-10\right)^2.3}+2\sqrt{\left(\sqrt{3}-\sqrt{5}\right)^2}\) b) \(\left(15\sqrt{50}+5\sqrt{200}-3\sqrt{450}\right):\sqrt{10}\)
c) \(\left(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}\right):\sqrt{6}\) d) \(\frac{\sqrt{5+2\sqrt{6}}+\sqrt{8-2\sqrt{15}}}{\sqrt{7+2\sqrt{10}}}\)
Rút gọn các biểu thức sau:a) left(sqrt{8}-3sqrt{2}+sqrt{10}right)left(sqrt{2}-3sqrt{0,4}right) b) left(sqrt{28}-2sqrt{14}+sqrt{7}right).sqrt{7}+7sqrt{8}c) 2sqrt{left(sqrt{2}-3right)^2}+sqrt{2left(-3right)^2}-5sqrt{left(-1right)^4} d) left(frac{sqrt{14}-sqrt{7}}{1-sqrt{2}}+frac{sqrt{15}-sqrt{5}}{1-sqrt{3}}right):frac{1}{sqrt{7}-sqrt{5}}
Đọc tiếp
Rút gọn các biểu thức sau:
a) \(\left(\sqrt{8}-3\sqrt{2}+\sqrt{10}\right)\left(\sqrt{2}-3\sqrt{0,4}\right)\) b) \(\left(\sqrt{28}-2\sqrt{14}+\sqrt{7}\right).\sqrt{7}+7\sqrt{8}\)
c) \(2\sqrt{\left(\sqrt{2}-3\right)^2}+\sqrt{2\left(-3\right)^2}-5\sqrt{\left(-1\right)^4}\) d) \(\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right):\frac{1}{\sqrt{7}-\sqrt{5}}\)
rút gọn các biểu thức a/ Asqrt{7+2sqrt{6}}+sqrt{7-2sqrt{6}}-2sqrt{6}b/ B sqrt{7+2sqrt{10}}-sqrt{7+2sqrt{10}}-sqrt{8}c/ Csqrt{14+4sqrt{6}}-sqrt{14-4sqrt{6}}d/ Dsqrt{3+sqrt{5}}-sqrt{3-sqrt{5}}e/ Efrac{sqrt{2-sqrt{3}}}{sqrt{2}}f/ Ffrac{sqrt{x-sqrt{2x-1}}}{sqrt{2}}vớifrac{1}{2}le x 1
Đọc tiếp
rút gọn các biểu thức
a/ A=\(\sqrt{7+2\sqrt{6}}+\sqrt{7-2\sqrt{6}}-2\sqrt{6}\)
b/ B= \(\sqrt{7+2\sqrt{10}}-\sqrt{7+2\sqrt{10}}-\sqrt{8}\)
c/ C=\(\sqrt{14+4\sqrt{6}}-\sqrt{14-4\sqrt{6}}\)
d/ D=\(\sqrt{3+\sqrt{5}}-\sqrt{3-\sqrt{5}}\)
e/ E=\(\frac{\sqrt{2-\sqrt{3}}}{\sqrt{2}}\)
f/ F=\(\frac{\sqrt{x-\sqrt{2x-1}}}{\sqrt{2}}với\frac{1}{2}\le x< 1\)
Rút gọn:a)(sqrt{8}-3sqrt{2}+sqrt{10}).sqrt{2}-sqrt{5}b)(frac{1}{2}sqrt{frac{1}{2}}-frac{3}{2}sqrt{2}+frac{4}{5}sqrt{200}):frac{1}{8}c)(frac{2sqrt{3}-sqrt{6}}{sqrt{8}-2}-frac{sqrt{216}}{3}).frac{1}{sqrt{6}}d)(frac{sqrt{14}-sqrt{2}}{1-sqrt{2}}+frac{sqrt{15}-sqrt{5}}{1-sqrt{3}}):frac{1}{sqrt{7}-sqrt{5}}
Đọc tiếp
Rút gọn:
a)(\(\sqrt{8}-3\sqrt{2}+\sqrt{10}\))\(.\sqrt{2}-\sqrt{5}\)
b)(\(\frac{1}{2}\sqrt{\frac{1}{2}}-\frac{3}{2}\sqrt{2}\)+\(\frac{4}{5}\sqrt{200}\))\(:\frac{1}{8}\)
c)(\(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}\))\(.\frac{1}{\sqrt{6}}\)
d)(\(\frac{\sqrt{14}-\sqrt{2}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\))\(:\frac{1}{\sqrt{7}-\sqrt{5}}\)
a)frac{4}{sqrt{5}-1}+frac{3}{sqrt{5}-2}+frac{16}{sqrt{5}-3} b)frac{2}{sqrt{8-2sqrt{15}}}-frac{1}{sqrt{5-2sqrt{6}}}-frac{3}{sqrt{7+2sqrt{10}}} c)frac{8+2sqrt{2}}{3-sqrt{2}}-frac{2+3sqrt{2}}{sqrt{2}}+frac{sqrt{2}}{1-sqrt{2}} d)sqrt{1+frac{sqrt{3}}{2}}-frac{sqrt{8-sqrt{15}}}{sqrt{30}-sqrt{2}}
Đọc tiếp
a)\(\frac{4}{\sqrt{5}-1}+\frac{3}{\sqrt{5}-2}+\frac{16}{\sqrt{5}-3}\)
b)\(\frac{2}{\sqrt{8-2\sqrt{15}}}-\frac{1}{\sqrt{5-2\sqrt{6}}}-\frac{3}{\sqrt{7+2\sqrt{10}}}\)
c)\(\frac{8+2\sqrt{2}}{3-\sqrt{2}}-\frac{2+3\sqrt{2}}{\sqrt{2}}+\frac{\sqrt{2}}{1-\sqrt{2}}\)
d)\(\sqrt{1+\frac{\sqrt{3}}{2}}-\frac{\sqrt{8-\sqrt{15}}}{\sqrt{30}-\sqrt{2}}\)
rút gọn
a,\(\dfrac{\sqrt{10}-\sqrt{15}}{\sqrt{8}-\sqrt{12}}\) b,\(\dfrac{\sqrt{15}-\sqrt{6}}{\sqrt{35}-\sqrt{14}}\) c,\(\dfrac{5+\sqrt{5}}{\sqrt{10}+\sqrt{2}}\)
rút gọna) left(-7sqrt{7}right)left(-2sqrt{8}right)b) -sqrt{33}.3sqrt{3}c) left(3sqrt{5}right).left(-10sqrt{3}right)d) dfrac{1}{2}sqrt{5}.left(-6sqrt{2}right)e) dfrac{2}{3}sqrt{7}.left(-dfrac{9}{16}sqrt{3}right)f) 15sqrt{6}:5sqrt{3}g) -25sqrt{12}:left(-5sqrt{6}right)h) 36sqrt{8}:12sqrt{2}i) 4sqrt{27}:left(-2sqrt{3}right)
Đọc tiếp
rút gọn
a) \(\left(-7\sqrt{7}\right)\left(-2\sqrt{8}\right)\)
b) \(-\sqrt{33}.3\sqrt{3}\)
c) \(\left(3\sqrt{5}\right).\left(-10\sqrt{3}\right)\)
d) \(\dfrac{1}{2}\sqrt{5}.\left(-6\sqrt{2}\right)\)
e) \(\dfrac{2}{3}\sqrt{7}.\left(-\dfrac{9}{16}\sqrt{3}\right)\)
f) \(15\sqrt{6}:5\sqrt{3}\)
g) \(-25\sqrt{12}:\left(-5\sqrt{6}\right)\)
h) \(36\sqrt{8}:12\sqrt{2}\)
i) \(4\sqrt{27}:\left(-2\sqrt{3}\right)\)