0,5.\(\sqrt{100}\) - .\(\sqrt{81}\)
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`#3107.101107`
a)
`2/5 \sqrt{25} - 1/2 \sqrt{4}`
`= 2/5 * \sqrt{5^2} - 1/2 * \sqrt{2^2}`
`= 2/5*5 - 1/2*2`
`= 2 - 1`
`= 1`
b)
`0,5*\sqrt{0,09} + 5*\sqrt{0,81}`
`= 0,5*\sqrt{(0,3)^2} + 5*\sqrt{(0,9)^2}`
`= 0,5*0,3 + 5*0,9`
`= 0,15 + 4,5`
`= 4,65`
c)
`2/5\sqrt{25/36} - 5/2\sqrt{4/25}`
`= 2/5*\sqrt{(5^2)/(6^2)} - 5/2*\sqrt{(2^2)/(5^2)}`
`= 2/5*5/6 - 5/2*2/5`
`= 1/3 - 1`
`= -2/3`
d)
`-2 \sqrt{(-36)/(-16)} + 5 \sqrt{(-81)/(-25)}`
`= -2*\sqrt{36/16} + 5*\sqrt{81/25}`
`= -2*\sqrt{(6^2)/(4^2)} + 5*\sqrt{(9^2)/(5^2)}`
`= -2*6/4 + 5*9/5`
`= -3 + 9`
`= 6`
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(=3^2+\left(3^4\right)^{-0.75}-5^{2\cdot0.5}\)
\(=9-5+3^{-3}=4+\dfrac{1}{27}=\dfrac{109}{27}\)
b: \(=2^{4-6\sqrt{7}}\cdot2^{6\sqrt{7}}=2^{4-6\sqrt{7}+6\sqrt{7}}=2^4=16\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(100\times\sqrt{0,01}-0,5\times\sqrt{400}+\sqrt{0,09}=100\times0,1-0,5\times20+0,3\)
\(=10-10+0,3=0+0,3=0,3\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, = \(\sqrt{2}\)/2 - 1/2 = \(\sqrt{2}-1\)/2
b, = 0,5 . 10 - 1/2 = 5 - 1/2 =9/2
Đáp án là:
a) = \(\frac{-1+\sqrt{2}}{2}\) .
b) = \(\frac{9}{2}\) .
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
\(A=\sqrt{1}+\sqrt{4}+\sqrt{9}+...+\sqrt{81}+\sqrt{100}\)
\(=\sqrt{1^2}+\sqrt{2^2}+\sqrt{3^2}+...+\sqrt{9^2}+\sqrt{10^2}\)
\(=1+2+3+....+9+10=\frac{10(10+1)}{2}=55\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\sqrt{1}\)=1
\(\sqrt{4}\)=2
....
\(\sqrt{100}\)=10
=> A= 1+2+...+10=55
Ta có: A =\(\sqrt{1}+\sqrt{4}+\sqrt{9}+...+\sqrt{81}+\sqrt{100}\)
= \(\sqrt{1^2}+\sqrt{2^2}+\sqrt{3^2}+...+\sqrt{9^2}+\sqrt{10^2}\)
= |1| + |2| + |3| + ...+ |9| + |10|
= 1 + 2 + 3 + 4 +...+ 9 + 10
= 55
0.5.10-9=-4
cảm ơn bạn nhiều