a) (x - 2,5)^2 = 9
b)(1 - x)^3 = -8
c)2^4-x = 16
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20 tháng 6 2023
a: =>x:1/2=5/9
=>x=10/9
b: =>x*2/5=7/3
=>x=7/3:2/5=7/3*5/2=35/6
c: =>x=7/8-9/16=5/16
10 tháng 4 2018
a, x= 2 x 2,5x 3,1
x=15,5
b, x= 32,8:1,2;8,2
x=10/3
c, x=(3/4x15/16 +1) :3
x=109/192
d, x= 2,x13,7:2,5-3,7
x=10
k cho mình nha!
19 tháng 11 2021
Câu 2:
\(\dfrac{a+b}{6}=\dfrac{b+c}{7}=\dfrac{c+a}{8}=\dfrac{2\left(a+b+c\right)}{6+7+8}=\dfrac{28}{21}=\dfrac{4}{3}\\ \Rightarrow\left\{{}\begin{matrix}a+b=\dfrac{4}{3}\cdot6=8\\b+c=\dfrac{4}{3}\cdot7=\dfrac{28}{3}\\c+a=\dfrac{4}{3}\cdot8=\dfrac{32}{3}\end{matrix}\right.\\ \Rightarrow\left\{{}\begin{matrix}a=14-\dfrac{28}{3}=\dfrac{14}{3}\\b=14-\dfrac{32}{3}=\dfrac{10}{3}\\c=14-8=6\end{matrix}\right.\)
Vậy chọn C
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15 tháng 4 2018
1,
\(\dfrac{6}{7}\) + \(\dfrac{-5}{8}\) : (-5) -\(\dfrac{3}{16}\) . \(\left(-2\right)^2\)
= \(\dfrac{6}{7}\) + \(\dfrac{-5}{8}\) . \(\dfrac{-1}{5}\) - \(\dfrac{3}{16}\) . 4
= \(\dfrac{6}{7}\) + \(\dfrac{1}{8}\) - \(\dfrac{3}{4}\)
= \(\dfrac{48}{56}\) + \(\dfrac{7}{56}\) - \(\dfrac{42}{56}\)
= \(\dfrac{13}{56}\)
3,
a,\(\dfrac{3}{5}\)x - \(\dfrac{7}{10}\)x = \(\dfrac{-1}{2}\)
x.(\(\dfrac{3}{5}\) - \(\dfrac{7}{10}\)) = \(\dfrac{-1}{2}\)
x.\(\dfrac{-1}{10}\)= \(\dfrac{-1}{2}\)
x =\(\dfrac{-1}{2}\):\(\dfrac{-1}{10}\)
x = 5
c, (2,5x - 3,6) : \(\dfrac{15}{7}\) = -1
( \(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\)) : \(\dfrac{15}{7}\) = -1
\(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\) = -1 . \(\dfrac{15}{7}\)
\(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\) = \(\dfrac{-15}{7}\)
\(\dfrac{5}{2}\)x = \(\dfrac{-15}{7}\) + \(\dfrac{18}{5}\)
\(\dfrac{5}{2}\)x = \(\dfrac{51}{35}\)
x =\(\dfrac{51}{35}\) : \(\dfrac{5}{2}\)
x = \(\dfrac{102}{175}\)
Mình không biết có chỗ nào sai không nữa.
a) \(\left(x-2,5\right)^2=9\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2,5=3\\x-2,5=-3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=5,5\\x=-0,5\end{matrix}\right.\)
b) \(\left(1-x\right)^3=-8=\left(-2\right)^3\)
\(1-x=-2\)
\(x=3\)
c) \(2^4-x=16\)
\(16-x=16\)
\(x=0\)
\(a,\left(x-2,5\right)^2=9\)
\(+,TH1:x-2,5=3\)
\(\Rightarrow x=3+2,5\\\Rightarrow x=5,5\)
\(+,TH2:x-2,5=-3\)
\(\Rightarrow x=-3+2,5\\\Rightarrow x=-0,5\)
\(b,(1-x)^3=-8\)
\(\Rightarrow\left(1-x\right)^3=\left(-2\right)^3\)
\(\Rightarrow1-x=-2\)
\(\Rightarrow x=1-\left(-2\right)\)
\(\Rightarrow x=3\)
\(c,2^4-x=16\)
\(\Rightarrow16-x=16\)
\(\Rightarrow x=0\)
#\(Toru\)