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a) Ta có:
\(5\sqrt{a}-4b\sqrt{25a^3}+5a\sqrt{16ab^2}-2\sqrt{9a}\)
\(=5\sqrt{a}-4b.5a\sqrt{a}+5a.4b\sqrt{a}-2.3\sqrt{a}\)
\(=5\sqrt{a}-20ab\sqrt{a}+20ab\sqrt{a}-6\sqrt{a}\) \(=-\sqrt{a}\)
b) Ta có:
\(5a\sqrt{64ab^3}-\sqrt{3}.\sqrt{12a^3b^3}+2ab\sqrt{9ab}\) \(-5b\sqrt{81a^3b}\)
\(=5a.8b\sqrt{ab}-\sqrt{3.12a^3b^3}+2ab.3\sqrt{ab}\) \(-5b.9a\sqrt{ab}\)
\(=40ab\sqrt{ab}-6ab\sqrt{ab}+6ab\sqrt{ab}-45ab\)\(\sqrt{ab}\)
\(=-5ab\sqrt{ab}\)
a) Ta có: \(5\sqrt{a}-3\sqrt{25a^3}+2\sqrt{36ab^2}-2\sqrt{9a}\)
\(=5\sqrt{a}-15a\sqrt{a}+12b\sqrt{a}-6\sqrt{a}\)
\(=-\sqrt{a}-15a\sqrt{a}+12\sqrt{a}b\)
b) Ta có: \(\sqrt{64ab^3}-3\sqrt{12a^3b^3}+2ab\sqrt{9ab}-5b\sqrt{81a^3b}\)
\(=8b\sqrt{a}-6ab\sqrt{3ab}+6ab\sqrt{ab}-45a^2b\sqrt{ab}\)
a)\(5\sqrt{a}-3\sqrt{25a^3}+2\sqrt{36ab^2}-2\sqrt{9a}=5\sqrt{a}-15\left|a\right|\sqrt{a}+12\left|b\right|\sqrt{a}-6\sqrt{a}=-\sqrt{a}-15a\sqrt{a}+12b\sqrt{a}\)
b)\(\sqrt{64ab^3}-3\sqrt{12a^3b^3}+2ab\sqrt{9ab}-5b\sqrt{81a^3b}\)
\(=8\left|b\right|\sqrt{ab}-6\left|ab\right|\sqrt{3ab}+6ab\sqrt{ab}-45b\left|a\right|\sqrt{ab}\)
\(=8b\sqrt{ab}-6ab\sqrt{3ab}+6ab\sqrt{ab}-45ab\sqrt{ab}\)
\(=8b\sqrt{ab}-6ab\sqrt{3ab}-39ab\sqrt{ab}\)
a) Ta có: \(\sqrt{125}-4\sqrt{45}+3\sqrt{20}-\sqrt{80}\)
\(=5\sqrt{5}-4.3\sqrt{5}+3.2\sqrt{5}-4\sqrt{5}\)
\(=5\sqrt{5}-12\sqrt{5}+6\sqrt{5}-4\sqrt{5}\)
\(=-5\sqrt{5}\)
\(\approx-11,18033989\)
\(5a\sqrt{64ab^3}-\sqrt{3}\cdot\sqrt{12a^3b^3}+2ab\sqrt{9ab}-5b\sqrt{81a^3b}\\ =5a\cdot8b\sqrt{ab}-\sqrt{3\cdot12a^3b^3}+2ab\cdot3\sqrt{ab}-5b\cdot9a\sqrt{ab}\\ =40ab\sqrt{ab}-6ab\sqrt{ab}+6ab\sqrt{ab}-45ab\sqrt{ab}\\ =-5ab\sqrt{ab}\)
\(\sqrt{64ab^3}-3\sqrt{12a^3b^3}+2ab\sqrt{9ab}-5b\sqrt{81a^3b}\\ =\sqrt{64b^2.ab}-3\sqrt{4a^2b^2.ab}+2ab.3\sqrt{ab}-5b\sqrt{81a^2.ab}\\ =\left|8b\right|\sqrt{ab}+3\left|2ab\right|\sqrt{3ab}+6ab\sqrt{ab}-5b\left|9a\right|\sqrt{ab}\\ =8b\sqrt{ab}-6ab\sqrt{3ab}-39ab\sqrt{ab}\\ \)
a: \(=6\sqrt{a}+\dfrac{1}{3}\sqrt{a}-3\sqrt{a}+\sqrt{7}=\dfrac{10}{3}\sqrt{a}+\sqrt{7}\)
b: \(=5a\cdot5b\sqrt{ab}+\sqrt{3}\cdot2\sqrt{3}\cdot ab\sqrt{ab}+9ab\cdot3\sqrt{ab}-5b\cdot9a\sqrt{ab}\)
\(=25ab\sqrt{ab}+12ab\sqrt{ab}+27ab\sqrt{ab}-45ab\sqrt{ab}\)
\(=19ab\sqrt{ab}\)
c: \(=\dfrac{\sqrt{ab}}{b}+\sqrt{ab}-\dfrac{a}{b}\cdot\dfrac{\sqrt{b}}{\sqrt{a}}\)
\(=\sqrt{ab}\left(\dfrac{1}{b}+1\right)-\dfrac{\sqrt{a}}{\sqrt{b}}\)
\(=\sqrt{ab}\)
d: \(=11\sqrt{5a}-5\sqrt{5a}+2\sqrt{5a}-12\sqrt{5a}+9\sqrt{a}\)
\(=-4\sqrt{5a}+9\sqrt{a}\)
Ta có: \(5a\sqrt{64ab^3}-\sqrt{3}.\sqrt{12a^3b^3}-5b\sqrt{81a^3b}\)
\(=5a.8b.\sqrt{ab}-\sqrt{3}.2\sqrt{3}.ab.\sqrt{ab}-5b.9a\sqrt{ab}\)
\(=40ab.\sqrt{ab}-6ab.\sqrt{ab}-45ab.\sqrt{ab}\)
\(=40ab.\sqrt{ab}-6ab.\sqrt{ab}-45ab.\sqrt{ab}\)
\(=-11ab\sqrt{ab}\)
\(5a\sqrt{64ab^3}\) \(-\sqrt{3}\)\(.\sqrt{12a^3b^3}\)\(-5b\sqrt{81a^3b}\)
\(=40ab\sqrt{ab}\)\(-6ab\sqrt{ab}-45ab\sqrt{ab}\)
\(=\left(40ab-6ab-45ab\right)\sqrt{ab}\)
\(=-11ab\sqrt{ab}\)
\(5\sqrt{a}-4b\sqrt{25^3}+5a\sqrt{16ab^2}-2\sqrt{9a}\)
\(=5\sqrt{a}-4b.25a\sqrt{a}+5a.4b\sqrt{a}-6\sqrt{a}\)
\(=5\sqrt{a}-20ab\sqrt{a}+20ab\sqrt{a}-6\sqrt{a}\)
\(=-\sqrt{a}\)
