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!

a, x= 15.5

b x= 10/3

c x= 0.6

d x= 10

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) \(2^4-x=16\)

\(16-x=16\)

\(x=0\)

\(a,\left(x-2,5\right)^2=9\)

\(+,TH1:x-2,5=3\)

\(\Rightarrow x=3+2,5\\\Rightarrow x=5,5\)

\(+,TH2:x-2,5=-3\)

\(\Rightarrow x=-3+2,5\\\Rightarrow x=-0,5\)

\(b,(1-x)^3=-8\)

\(\Rightarrow\left(1-x\right)^3=\left(-2\right)^3\)

\(\Rightarrow1-x=-2\)

\(\Rightarrow x=1-\left(-2\right)\)

\(\Rightarrow x=3\)

\(c,2^4-x=16\)

\(\Rightarrow16-x=16\)

\(\Rightarrow x=0\)

#\(Toru\)

a) 3x-1=16*3/4*15

3x=48/60+60/60

3x=108/60

x=0,6

b) 2,5*(x+3,7)=34,25

x+3,7=13,7

x=10

a) 1/3 * x + 2/5 = 3/2 

    1/3 * x          = 3/2 - 2/5 

    1/3  * x         = 15/10 - 4/10 

    1/3  * x        = 11/10 

            x         = 11/10 : 1/3 

           x          = 11/10 * 3 

          x           = 33/10 

a) x=\(\frac{33}{10}\)

b)x=\(\frac{1}{4}\)

c) x=15

16 : (0,3 * x +2,5) : x = 17 + 3= 20

 -> \(\frac{0,3\times x+2,5}{x}=\frac{16}{20}=\frac{4}{5}\)

    \(\frac{0,3\times x}{x}+\frac{2,5}{x}=\frac{4}{5}\)

        \(0,3+\frac{2,5}{x}=\frac{4}{5}\)

                      \(\frac{2,5}{x}=\frac{4}{5}-0,3\)

                      \(\frac{2,5}{x}=\frac{1}{2}\)

                       \(x=2,5:\frac{1}{2}=5\)

Mình thay x là a nha:

16 : (0,3 x a + 2,5) : a - 3 = 17

(16 : 0,3 x 16 :a + 26 : 2,5) : a = 17 + 3

(\(\frac{160}{3}\) x \(\frac{16}{a}\) + \(\frac{52}{5}\)) : a = 20

\(\frac{160}{3}\) : a x \(\frac{16}{a}\) :a + \(\frac{52}{5}:a\)= 20

\(\frac{160}{3a}\times\frac{16}{a\times a}+\frac{52}{5a}=20\)

... 

16:(0,3+2,5/x)-3=17

=>16:(0,3+2,5/x)=17+3=20

=>0,3+2,5/x=16:20=4/5

=>2,5/x=4/5-0,3=1/2

=>x=1/2x2,5=5/4

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.