(x-3 /4)^2 = 16 /25
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12-|x|=8
=> |x|= 12-8= 4
=> x= 4 hoặc x= -4
T I C K cái nha, tí lm tiếp vài câu nữa, chờ tí
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1) Ta có: \(\left(-\dfrac{2}{3}\right)^2\cdot\dfrac{-9}{8}-25\%\cdot\dfrac{-16}{5}\)
\(=\dfrac{4}{9}\cdot\dfrac{-9}{8}-\dfrac{1}{4}\cdot\dfrac{-16}{5}\)
\(=\dfrac{-1}{2}+\dfrac{4}{5}\)
\(=\dfrac{-5}{10}+\dfrac{8}{10}=\dfrac{3}{10}\)
2) Ta có: \(-1\dfrac{2}{5}\cdot75\%+\dfrac{-7}{5}\cdot25\%\)
\(=\dfrac{-7}{5}\cdot\dfrac{3}{4}+\dfrac{-7}{5}\cdot\dfrac{1}{4}\)
\(=\dfrac{-7}{5}\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=-\dfrac{7}{5}\)
3) Ta có: \(-2\dfrac{3}{7}\cdot\left(-125\%\right)+\dfrac{-17}{7}\cdot25\%\)
\(=\dfrac{-17}{7}\cdot\dfrac{-5}{4}+\dfrac{-17}{7}\cdot\dfrac{1}{4}\)
\(=\dfrac{-17}{7}\cdot\left(\dfrac{-5}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{17}{7}\)
4) Ta có: \(\left(-2\right)^3\cdot\left(\dfrac{3}{4}\cdot0.25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
\(=\left(-8\right)\cdot\left(\dfrac{3}{4}\cdot\dfrac{1}{4}\right):\left(\dfrac{9}{4}-\dfrac{7}{6}\right)\)
\(=\left(-8\right)\cdot\dfrac{3}{16}:\dfrac{54-28}{24}\)
\(=\dfrac{-3}{2}\cdot\dfrac{24}{26}\)
\(=\dfrac{-72}{52}=\dfrac{-18}{13}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 410. 230=220.230=250
b,925.274.813= 350.312.312=374
Tương tự các câu khác....
a, 410.230 = (22)10.230 = 220.230 = 250
b, 925.274.813 = (32)25.(33)4.(34)3 = 350.312.312 = 374
c, 2550.1255 = (52)50.(53)5 = 5100.515 = 5115
d, 643.48.164 = (26)3.(22)8.(24)4 = 218.216.216 = 250
e, 38 : 36 = 32
210 : 83 = 210 : (23)3 = 210 : 29 = 2
127 : 67 = (12 : 6)7 = 27
@Dương Tuyết Mai
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125(28+72)-25(3^2.4+64)
=125.100-25(9.4+64)
=125.100-25.(36+64)
=125.100-25.100
=12500-2500
=10000
![](https://rs.olm.vn/images/avt/0.png?1311)
11/15 + 8/5= Tính phân số
6/7 - 5/21=
25/4 x 16/100
7 x 2/49 =
4/3 : 2/9
5/8 : 25 =
`(x-3/4)^2 = 16/25`
`(x-3/4)^2 = (4/5)^2`
`x-3/4 = 4/5`
Xét `2` trường hợp :
`@TH1:`
`x-3/4=4/5`
`x=4/5+3/4`
`x=16/20 + 15/20`
`x=31/20`
Vậy `x = 31/20`
`@TH2:`
`x-3/4 = -4/5`
`x=-4/5 + 3/4`
`x=-16/20 + 15/20`
`x=-1/20`
Vậy `x = -1/20`
\(\left(x-\dfrac{3}{4}\right)^2=\dfrac{16}{25}\)
\(\left(x-\dfrac{3}{4}\right)^2=\left(\dfrac{4}{5}\right)^2\)
\(x-\dfrac{3}{4}=\dfrac{4}{5}\)
\(x=\dfrac{4}{5}+\dfrac{3}{4}\)
\(x=\dfrac{31}{20}\)