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\(\sqrt{2,5}.\sqrt{360}\)
\(=\sqrt{25}.\sqrt{36}\)
\(=5.6\)
\(=30\)
\(\sqrt{\frac{-49}{-121}}\)
\(=\sqrt{\frac{49}{121}}\)
\(=\frac{\sqrt{49}}{\sqrt{121}}=\frac{7}{11}\)
a) \(\sqrt{36}.\sqrt{121}+\sqrt[3]{-64}-\sqrt[3]{125}\)
\(=6.11+\left(-4\right)-5=66-9=57\)
b) \(\sqrt{75}+\sqrt{\left(\sqrt{3}-2\right)^2}-30\sqrt{\frac{3}{25}}\)
\(=\sqrt{25.3}+\left|\sqrt{3}-2\right|-30.\frac{\sqrt{3}}{\sqrt{25}}\)
\(=5\sqrt{3}+2-\sqrt{3}-30.\frac{\sqrt{3}}{5}\)
\(=5\sqrt{3}+2-\sqrt{3}-6\sqrt{3}=2-2\sqrt{3}\)
c) \(\sqrt{11-4\sqrt{7}}-\frac{12}{1+\sqrt{7}}=\sqrt{7-4\sqrt{7}+4}-\frac{12}{1+\sqrt{7}}\)
\(=\sqrt{\left(\sqrt{7}-2\right)^2}-\frac{12}{1+\sqrt{7}}=\left|\sqrt{7}-2\right|-\frac{12}{1+\sqrt{7}}\)
\(=\left(\sqrt{7}-2\right)-\frac{12}{\sqrt{7}+1}=\frac{\left(\sqrt{7}-2\right)\left(\sqrt{7}+1\right)}{\sqrt{7}+1}-\frac{12}{\sqrt{7}+1}\)
\(=\frac{5-\sqrt{7}}{\sqrt{7}+1}-\frac{12}{\sqrt{7}+1}=\frac{-7-\sqrt{7}}{\sqrt{7}+1}\)
\(=\frac{-\sqrt{7}\left(\sqrt{7}+1\right)}{\sqrt{7}+1}=-\sqrt{7}\)
a) Ta có: \(\sqrt{45}:\sqrt{80}\)
\(=\sqrt{\frac{45}{80}}=\sqrt{\frac{9}{20}}\)
\(=\frac{3}{2\sqrt{5}}\)
b) Ta có: \(\sqrt{\frac{3}{15}}:\sqrt{\frac{36}{45}}\)
\(=\sqrt{\frac{1}{5}:\frac{4}{5}}\)
\(=\sqrt{\frac{1}{5}\cdot\frac{5}{4}}\)
\(=\sqrt{\frac{1}{4}}=\frac{1}{2}\)
c) Ta có: \(\sqrt{\frac{72}{9}}:\sqrt{8}\)
\(=\frac{\sqrt{8}}{\sqrt{8}}=1\)
d) Ta có: \(\sqrt{\frac{288}{169}}:\sqrt{\frac{8}{225}}\)
\(=\sqrt{\frac{288}{169}:\frac{8}{225}}\)
\(=\sqrt{\frac{288}{169}\cdot\frac{225}{8}}\)
\(=\sqrt{\frac{8100}{169}}=\frac{90}{13}\)
tu lam di cau nao kho thi hoi hoi vay ko ai tra loi cho dau
cau e)
\(A=\sqrt{2+\sqrt{3}}.\sqrt{2-\sqrt{3}}\)(suy ra A>=0)
\(A^2=\left(2+\sqrt{3}\right)\left(2-\sqrt{3}\right)\)
\(A^2=1\)
A=1
(bai toan co nhieu cach)
cau m)
\(=\frac{\sqrt{\left(\sqrt{3}+\sqrt{2}\right)^2}+\sqrt{\left(\sqrt{5}-\sqrt{3}\right)^2}}{\sqrt{\left(\sqrt{5}+\sqrt{2}\right)^2}}\)
\(=\frac{\sqrt{3}+\sqrt{2}+\sqrt{5}-\sqrt{3}}{\sqrt{5}+\sqrt{2}}\)
\(=1\)
cau G)
\(=\frac{5\sqrt{7}}{\sqrt{35}}-\frac{7\sqrt{5}}{\sqrt{35}}+\frac{2\sqrt{70}}{\sqrt{35}}\)
\(=\frac{5}{\sqrt{5}}-\frac{7}{\sqrt{7}}+2\sqrt{2}\)
\(=\sqrt{5}-\sqrt{7}+2\sqrt{2}\)
1) \(\sqrt{\frac{24}{3}}\cdot\sqrt{\frac{3a}{8}}=\sqrt{\frac{72a}{24}}=\sqrt{3a}\)
2) \(\sqrt{13a}\cdot\sqrt{\frac{52}{a}}=\sqrt{\frac{13a\cdot52}{a}}=\sqrt{676}=26\)
3) \(\sqrt{5a}\cdot\sqrt{45a}-3a=\sqrt{225a^2}-3a=15a-3a=12a\)
4) \(\left(3-a\right)^2-\sqrt{0,2}\cdot\sqrt{180a^2}=a^2-6a+9-\sqrt{36a^2}=a^2-6a+9-6a=a^2-12a+9\)
ĐKXĐ: \(x\ge0\)
Từ biểu thức đầu suy ra: \(7\left(5\sqrt{x}-2\right)=2\left(8\sqrt{x}+2,5\right)\)
⇒ \(35\sqrt{x}-14=16\sqrt{x}+5\)
⇒ \(19\sqrt{x}=19\Rightarrow x=1\)(Thỏa mãn ĐKXĐ)
\(\sqrt{8,1}.\sqrt{250}\)
\(=\sqrt{81}.\sqrt{25}\)
\(=9.5\)
\(=45\)
\(\sqrt{2,5}.\sqrt{360}\)
\(=\sqrt{25}.\sqrt{36}\)
\(=5.6\)
\(=30\)
\(\sqrt{\frac{-49}{-121}}=\sqrt{\frac{49}{121}}\)
\(=\frac{\sqrt{49}}{\sqrt{121}}\)
\(=\frac{7}{11}\)
\(\sqrt{\frac{-36}{-169}}=\sqrt{\frac{36}{169}}\)
\(=\frac{\sqrt{36}}{\sqrt{169}}=\frac{6}{13}\)