25%-0,5*2/5
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a: \(=\dfrac{5}{4}\cdot\dfrac{2}{5}\cdot\dfrac{17}{21}\cdot\dfrac{7}{34}=\dfrac{1}{2}\cdot\dfrac{1}{2}\cdot\dfrac{1}{3}=\dfrac{1}{12}\)
b: =>0,5^x(0,5+1)=1,5
=>0,5^x=1
=>x=0
c: =>x*0,05-0,25*x=-1,2
=>-0,3*x=-1,2
=>x=4
d: =>x-1=1 hoặc x-1=-1
=>x=0 hoặc x=2
e: =5+4=9
`#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`
\(=\dfrac{25}{100}-\dfrac{3}{2}+\dfrac{1}{2}.\dfrac{12}{5}=\dfrac{1}{4}-\dfrac{3}{2}+\dfrac{6}{5}=\dfrac{5}{20}-\dfrac{30}{20}+\dfrac{24}{20}=\dfrac{-1}{20}\)
a) -7/25 . 11/13 + -7/25 . 2/13 - 18/25=-1
b) 5/7 . 1/3 - 5/7 . 1/4 - 5/7 . 1/12=0
c) 5 + 2/5 . 4+ 2/7 + 5 + 5/7 . 5+ 2/5=18
d) 75% - 3/2 + 0,5 - [ -1/2]^2=-1/2
\(\text{a)}25\%-\frac{3}{2}+0,5.\frac{12}{5}\)
\(=\frac{1}{4}-\frac{3}{2}+\frac{1}{2}.\frac{12}{5}\)
\(=-\frac{5}{8}+\frac{6}{5}\)
\(=-\frac{25}{40}+\frac{48}{40}\)
\(=\frac{23}{40}\)
\(b)0,25.\frac{7}{3}.30.\text{ }0,5.\frac{8}{45}\)
\(=\frac{1}{4}.\frac{7}{3}.30.\frac{1}{2}.\frac{8}{45}\)
\(=\frac{7}{12}.(30.\frac{8}{90})\)
\(=\frac{7}{12}.\frac{8}{3}\)
\(=\frac{14}{9}\)
\(c)\frac{9}{23}.\frac{5}{8}+\frac{9}{23}.\frac{3}{8}-\frac{9}{23}\)
\(=\frac{9}{23}.\left(\frac{5}{8}+\frac{3}{8}-1\right)\)
\(=\frac{9}{23}.0\)
\(=0\)
\(25\%-2\frac{1}{3}+0,5.\frac{12}{5}\)
\(=\frac{1}{4}-\frac{7}{3}+\frac{1}{2}.\frac{12}{5}\)
\(=\frac{1}{4}-\frac{7}{3}+\frac{6}{5}\)
\(=\frac{1}{4}+\frac{-7}{3}+\frac{6}{5}\)
\(=\frac{15}{60}+\frac{-140}{60}+\frac{72}{60}\)
\(=\frac{-53}{60}\)
25% - 1 1/2 + 0,5 . 12/5
= 1/4 - 3/2 + 1/2 . 12 /5
= 1/4 - 3/2 + 6/5
= -5/4 + 6/5
= -1/20
25% - 1 1/2 + 0.5 x 12/5
= 0.25 - 1.5 + 0.5 x 2.4
= 0.25 - 1.5 + 1.2
= 0.25 - 2.7
= -2.45
35,5 : 0,125 + 35,5 x 2
= 35,5 x 8 + 35,5 x 2
= 35,5 x (8+2)
= 35,5 x 10
= 355
25,5 : 0,5 + 25,5 x 8
= 25,5 x 2 + 25,5 x 8
= 25,5 x (2+8)
= 25,5 x 10
= 255