a) \(\sqrt{16}\).\(\sqrt{25}\)+\(\sqrt{196}\):\(\sqrt{49}\)

=4.5+14/7

=20+2

=22

a) \(\sqrt{16}\).\(\sqrt{25}\) + \(\sqrt{196}\) : \(\sqrt{49}\) = 4.5+14:9=22

b) 36:\(\sqrt{2.3^2.18}\) - \(\sqrt{169}\)= 36 :  \(\)18 - 13 = -11

c) \(\sqrt{\sqrt{81}}\) = 3

d) \(\sqrt{3^2+4^2}\)= \(\sqrt{25}\)=5

a) (\(\sqrt{3}\)-1)²=3-2\(\sqrt{3}\)+1= 4-2\(\sqrt{3}\) (ĐPCM)

b) \(\sqrt{4-2\sqrt{3}}\)=\(\sqrt{3}\)-1 >0

Bình phương 2 vế, ta có:

4-2\(\sqrt{3}\)=3-2\(\sqrt{3}\)+1= 4-2\(\sqrt{3}\) (ĐPCM)

a)  \(\left(\sqrt{3}-1\right)^2\)=\(\left(\sqrt{3}\right)^2\)- 2\(\sqrt{3}\) +1= 3- 2\(\sqrt{3}\) +1=4-2\(\sqrt{3}\)

b)  \(\sqrt{4-2\sqrt{3}}-\sqrt{3}\) = \(\sqrt{\left(\sqrt{3}-1\right)^2}\) - \(\sqrt{3}\)= \(|\sqrt{3}-1|\)-\(\sqrt{3}\)=\(\sqrt{3}\)-1-\(\sqrt{3}\)=-1

a) \(\sqrt{x^2}\)=7

=> x²=49

=> x={-7;7}

b) \(\sqrt{x^2}\)=|-8|=8

=> x²=64

=>x={-8;8}

c) \(\sqrt{4x^2}\)=6

4x²=36

=>x²=9

=> x={-3;3}

d)\(\sqrt{9x^2}\)=|-12|=12

=> 9x²=144

=> x²=16

=> x={-4;4}

a)x=+7 hoặc x= -7

b) x=8 hoặc x= -8

c)x=3 hoặc x =-3

d) x=4 hoặc x= -4

what đề bài đâu

a, \(\sqrt{\left(2-\sqrt{3}\right)^2}=\left|2-\sqrt{3}\right|=2-\sqrt{3}\)do \(2-\sqrt{3}>0\)

b, \(\sqrt{\left(3-\sqrt{11}\right)^2}=\sqrt{\left(\sqrt{11}-3\right)^2}=\left|\sqrt{11}-3\right|=\sqrt{11}-3\)

do \(\sqrt{11}-3>0\)

c, \(2\sqrt{a^2}=2\left|a\right|=2a\)do \(a\ge0\)

d, \(3\sqrt{\left(a-2\right)^2}=3\sqrt{\left(2-a\right)^2}=3\left|2-a\right|=3\left(2-a\right)=6-3a\)

do \(a< 2\)

a, \(\sqrt{\left(0,1\right)^2}=\left|0,1\right|=0,1\)do \(0,1>0\)

b, \(\sqrt{\left(-0,3\right)^2}=\sqrt{\left(0,3\right)^2}=\left|0,3\right|=0,3\)do \(0,3>0\)

c, \(-\sqrt{\left(-1,3\right)^2}=-\sqrt{\left(1,3\right)^2}=-\left|1,3\right|=-1,3\)do \(1,3>0\)

d, \(-0,4\sqrt{\left(-0,4\right)^2}=-0,4\sqrt{\left(0,4\right)^2}=-0,4.\left|0,4\right|=-0,4.0,4=-0,14\)

do \(0,4>0\)

\(\sqrt{\left(0,1\right)^2}=\left|0,1\right|=0,1\)

\(\sqrt{\left(-0,3\right)^2}=\left|-0,3\right|=0,3\)

\(-\sqrt{\left(-1,3\right)^2}=-\left|-1,3\right|=-1,3\)

\(-0,4\sqrt{\left(-0,4\right)^2}=-0,4\cdot\left|-0,4\right|=-0,16\)

a

căn có nghĩa 

\(\Leftrightarrow\frac{a}{3}\ge0\)   

\(\Leftrightarrow a\ge0\)   

b

căn có nghĩa 

\(\Leftrightarrow-5a\ge0\)   

\(\Leftrightarrow b\le0\left(-5\le0\right)\)   

c

căn có nghĩa 

\(\Leftrightarrow4-a\ge0\)   

\(\Leftrightarrow-a\ge0-4\)   

\(\Leftrightarrow-a\ge-4\)   

\(\Leftrightarrow a\le4\)   

d

căn có nghĩa

\(\Leftrightarrow3a+7\ge0\)   

\(\Leftrightarrow a\ge-\frac{7}{3}\)

a>0

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