B1: thực hiện phép tínha,\(\sqrt{\frac{72}{9}}\):\(\sqrt{8}\)b,( \(7\sqrt{48}\)+ \(3\sqrt{27}\)-\(2\sqrt{12}\)):\(\sqrt{3}\)c,( \(\sqrt{125}\)+\(\sqrt{245}\)-\(\sqrt{5}\)) : \(\sqrt{5}\)d,( \(\sqrt{\frac{1}{7}}\)- \(\sqrt{\frac{16}{7}}\) + \(\sqrt{7}\))...
Đọc tiếp
B1: thực hiện phép tính
a,\(\sqrt{\frac{72}{9}}\):\(\sqrt{8}\)
b,( \(7\sqrt{48}\)+ \(3\sqrt{27}\)-\(2\sqrt{12}\)):\(\sqrt{3}\)
c,( \(\sqrt{125}\)+\(\sqrt{245}\)-\(\sqrt{5}\)) : \(\sqrt{5}\)
d,( \(\sqrt{\frac{1}{7}}\)- \(\sqrt{\frac{16}{7}}\) + \(\sqrt{7}\)) : \(\sqrt{7}\)
\(a,\sqrt{\frac{72}{9}}:\sqrt{8}=\frac{\sqrt{72}}{\sqrt{9}}.\frac{1}{\sqrt{8}}\)
\(=\frac{6\sqrt{2}}{3}.\frac{1}{2\sqrt{2}}\)
\(=1\)
\(b,\left(7\sqrt{48}+3\sqrt{27}-2\sqrt{12}\right):\sqrt{3}=\left(28\sqrt{3}+9\sqrt{3}-4\sqrt{3}\right):\sqrt{3}\)
\(=33\sqrt{3}:\sqrt{3}\)
\(=33\)
\(c,\left(\sqrt{125}+\sqrt{245}-\sqrt{5}\right):\sqrt{5}=\left(5\sqrt{5}+7\sqrt{5}-\sqrt{5}\right):\sqrt{5}\)
\(=11\sqrt{5}:\sqrt{5}\)
\(=11\)
\(d,\left(\sqrt{\frac{1}{7}}-\sqrt{\frac{16}{7}}+\sqrt{7}\right):\sqrt{7}=\left(\frac{1}{\sqrt{7}}-\frac{4}{\sqrt{7}}+\frac{7}{\sqrt{7}}\right):\sqrt{7}\)
\(=\frac{4}{\sqrt{7}}.\frac{1}{\sqrt{7}}=\frac{4}{7}\)