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15 tháng 6 2017

minh văn nguyễn

29 tháng 10 2021

\(=2\sqrt{3a}-5\sqrt{3a}+\dfrac{3}{2}\sqrt{3a}-10\sqrt{3a}\)

\(=-\dfrac{23}{2}\sqrt{3a}\)

14 tháng 10 2018

\(2\sqrt{3a}-\sqrt{75a}+a\sqrt{\dfrac{13,5}{2a}}-\dfrac{2}{5}\sqrt{300a^2}\)

\(=2\sqrt{3a}-5\sqrt{3a}+a\sqrt{\dfrac{27a}{\left(2a\right)^2}}-\dfrac{2}{5}\sqrt{100a^2.300}\\ =2\sqrt{a}-5\sqrt{3a}+\dfrac{a.3}{2a}\sqrt{3a}-\dfrac{2}{5}\left|10a\right|\sqrt{3a}\\ =2\sqrt{3a}-5\sqrt{3a}+1,5\sqrt{3a}-4a\sqrt{3a}\\ =-1,5\sqrt{3a}-4a\sqrt{3a}\)

15 tháng 12 2019

\(2\sqrt{3a}-\sqrt{75a}+a\sqrt{\frac{6}{5}.\frac{5}{2a}}-\frac{2}{5}\sqrt{300a^3}\)

\(=2\sqrt{3a}-5\sqrt{3a}+a\sqrt{\frac{3}{2}}-\frac{2}{5}.10.a\sqrt{3a}\)

\(=-3\sqrt{3a}+\sqrt{\frac{3}{a}.a^2-4\sqrt{3a}}\)

\(=-3\sqrt{3a}+\sqrt{3a}-4a\sqrt{3a}\)

\(=-2\sqrt{3a}-4a\sqrt{3a}\)

\(=-2\sqrt{3a}\left(1+2a\right)\)

a: \(=-10\sqrt{2}+10-\left(18-2\cdot3\sqrt{2}\cdot5+25\right)\)

\(=-10\sqrt{2}+19-43+30\sqrt{2}\)

\(=-24+20\sqrt{2}\)

b: \(=2\sqrt{3a}-5\sqrt{3a}+a\cdot\sqrt{\dfrac{27}{4a}}-\dfrac{2}{5}\cdot10a\sqrt{3a}\)

\(=-3\sqrt{3a}-4a\sqrt{3a}+\sqrt{\dfrac{27a}{4}}\)

\(=-3\sqrt{3a}-4a\sqrt{3a}+\dfrac{3}{2}\sqrt{3a}\)

\(=\sqrt{3a}\left(-\dfrac{3}{2}-4a\right)\)

15 tháng 7 2017

a) \(\left(2-\sqrt{2}\right)\left(-5\sqrt{2}\right)-\left(3\sqrt{2}-5\right)^2\)

\(=-10\sqrt{2}+5.2-\left(18-30\sqrt{2}+25\right)\)

\(=-10\sqrt{2}+10-18+30\sqrt{2}-25\)

\(=20\sqrt{2}-33\)

b) câu b đề sai

16 tháng 7 2017

câu a, \(\left(2-\sqrt{2}\right)\left(-5\sqrt{2}\right)-\left(3\sqrt{2}-5\right)^2=-10\sqrt{2}+5.2-\left(8-30\sqrt{2}+25\right)\)

= \(-33+20\sqrt{2}\)

25 tháng 10 2020

a) Ta có: \(2\sqrt{3a}-\sqrt{12a^3}-5\cdot\sqrt{\frac{a}{3}}-\frac{1}{4}\cdot\sqrt{27a}\)

\(=2\sqrt{3a}-2a\sqrt{3a}-\frac{5\sqrt{a}}{\sqrt{3}}-\frac{1}{4}\cdot3\sqrt{3a}\)

\(=2\sqrt{3a}-\frac{3}{4}\sqrt{3a}-2a\sqrt{3a}-\frac{5\sqrt{a}}{\sqrt{3}}\)

\(=\frac{5}{4}\sqrt{3a}-2a\sqrt{3a}-5\sqrt{3a}\cdot\frac{1}{3}\)

\(=\frac{5}{4}\sqrt{3a}-\frac{5}{3}\sqrt{3a}-2a\sqrt{3a}\)

\(=\frac{-5}{12}\sqrt{3a}-2a\sqrt{3a}\)

b) Ta có: \(2a\sqrt{b+a}+\left(a+b\right)\cdot\sqrt{\frac{1}{a+b}}-\sqrt{a^3+a^2b}\)

\(=2a\sqrt{a+b}+\sqrt{\left(a+b\right)^2\cdot\frac{1}{a+b}}-a\sqrt{a+b}\)

\(=a\sqrt{a+b}+\sqrt{a+b}\)

\(=\left(a+1\right)\cdot\sqrt{a+b}\)

c) Ta có: \(2\sqrt{a}+5\sqrt{\frac{a}{9}}-a\sqrt{\frac{16}{a}}\cdot\sqrt{a^3}\)

\(=2\sqrt{a}+5\cdot\frac{\sqrt{a}}{3}-4a^2\)

\(=\frac{11}{3}\sqrt{a}-4a^2\)