(x + 1) + (x + 4) + (x + 7) + ... + (x + 28) = 155

=> (x + x + x + ... + x) + (1 + 4 + 7 + ... + 28) = 155

=> 10x + 145 = 155

=> 10x = 10

=> x = 1

vậy_

\(\frac{7}{5}+\left(\frac{2\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}{5\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}\right)\cdot x=\frac{16}{5}\)

\(\frac{2}{5}x=\frac{16}{5}-\frac{7}{5}\)

\(\frac{2}{5}x=\frac{9}{5}\)

 x      = \(\frac{9}{5}:\frac{2}{5}\)

x        = 9/2 

\(1\frac{2}{5}+\left(\frac{\frac{2}{7}+\frac{2}{17}+\frac{2}{37}}{\frac{5}{7}+\frac{5}{17}+\frac{5}{37}}\right).x=\frac{16}{5}\)

\(\frac{7}{5}+\left[\frac{2.\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}{5.\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}\right].x=\frac{16}{5}\)

\(\frac{7}{5}+\frac{2}{5}.x=\frac{16}{5}\)

\(\frac{2}{5}.x=\frac{16}{5}-\frac{7}{5}\)

\(\frac{2}{5}.x=\frac{9}{5}\)

\(x=\frac{9}{5}:\frac{2}{5}\)

\(x=\frac{9}{5}.\frac{5}{2}\)

\(x=\frac{9}{2}\)

\(\frac{7}{5}+\left(\frac{2\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}{5\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}\right).x=\frac{16}{5}\)

                                                \(\frac{2}{5}x=\frac{16}{5}-\frac{7}{5}\)

                                               \(\frac{2}{5}x=\frac{9}{5}\)

                                                    \(x=\frac{9}{5}\div\frac{2}{5}\)

                                                   \(x=\frac{9}{2}\)

\(1\frac{3}{5}+\left(\frac{\frac{2}{7}+\frac{2}{17}+\frac{2}{37}}{\frac{5}{7}+\frac{5}{17}+\frac{5}{37}}\right)x=\frac{16}{5}\)

\(\Rightarrow\frac{2\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}{5\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}.x=\frac{16}{5}-\frac{8}{5}\)

\(\Rightarrow\frac{2}{5}.x=\frac{8}{5}\)

\(\Rightarrow x=\frac{8}{5}:\frac{2}{5}=4\)

vậy x=4

=.8/5+((2*17*37+2*7*37+2*7*17)/(7*17*37))/((5*17*37+5*7*37+5*7*17)/(7*17*37))*x=16/5

=>8/5+((2*17*37+2*7*37+2*7*17)/(7*17*37))*((7*17*37)/(5*17*37+5*7*37+5*7*17))*x=16/5

=>8/5+(2(17*37+7*37+7*17))/(5(17*37+7*37+7*17))*x=16/5

=>8/5+(2/5)*x=16/5

=>(2/5)*x=16/5-8/5

=>(2/5)*x=8/5

=>x=(8/5)/(2/5)

=>x=4

Vậy x=4

ngothithuyhien  làm dài dòng quá !

8/5 + [(2/7 + 2/17 + 2/37)/(5/7 + 5/17 + 5/37)].x = 16/5

=> 8/5 + [(2/7 : 5/7) + (2/17 : 5/17) + (2/37 + 5/37)].x = 16/5

=> 8/5 + (2/5 + 2/5 + 2/5).x = 16/5

=> 8/5 + (2/5 . 3).x = 16/5

=> 8/5 + 1/1/5 .x = 16/5

=>          6/5 .x = 16/5 - 8/5

=>          6/5 .x = 1/3/5

=>                 x = 1/3/5 : 6/5 

=>                 x = 1/1/3

Có gì sai xin m.n giúp đỡ ^^ 

a) \(x+\left(-7\right)=-20\)

\(\Rightarrow x=-20+7\)

\(\Rightarrow x=-13\)

Vậy \(x=-13\)

b) \(8-x=-12\)

\(\Rightarrow x=8-\left(-12\right)\)

\(\Rightarrow x=20\)

Vậy \(x=20\)

c) \(|x|-7=-6\)

\(\Rightarrow|x|=-6+7\)

\(\Rightarrow|x|=1\)

\(\Rightarrow\orbr{\begin{cases}x=1\\x=-1\end{cases}}\)

Vậy \(x\in\left\{1;-1\right\}\)

d) \(5^2.2^2-7.|x|=65\)

\(\Rightarrow\left(5.2\right)^2-7.|x|=65\)

\(\Rightarrow10^2-7.|x|=65\)

\(\Rightarrow100-7.|x|=65\)

\(\Rightarrow7.|x|=35\)

\(\Rightarrow|x|=5\)

\(\Rightarrow\orbr{\begin{cases}x=5\\x=-5\end{cases}}\)

Vậy \(x\in\left\{5;-5\right\}\)

e) \(37-3.|x|=2^3-4\)

\(\Rightarrow37-3.|x|=8-4\)

\(\Rightarrow37-3.|x|=4\)

\(\Rightarrow3.|x|=33\)

\(\Rightarrow|x|=11\)

\(\Rightarrow\orbr{\begin{cases}x=11\\x=-11\end{cases}}\)

Vậy \(x\in\left\{11;-11\right\}\)

f) \(|x|+|-5|=|-37|\)

\(\Rightarrow|x|+5=37\)

\(\Rightarrow|x|=32\)

\(\Rightarrow\orbr{\begin{cases}x=32\\x=-32\end{cases}}\)

Vậy \(x\in\left\{32;-32\right\}\)

g)\(5.|x+9|=40\)

\(\Rightarrow|x+9|=8\)

\(\Rightarrow\orbr{\begin{cases}x+9=8\\x+9=-8\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-1\\x=-17\end{cases}}\)

Vậy \(x\in\left\{-1;-17\right\}\)

h) \(-\frac{5}{6}+\frac{8}{3}+\frac{-29}{6}\le x\le\frac{-1}{2}+2+\frac{5}{2}\)

\(\Rightarrow\frac{-5}{6}+\frac{16}{6}+\frac{-29}{6}\le x\le\frac{-1}{2}+\frac{4}{2}+\frac{5}{2}\)

\(\Rightarrow-3\le x\le4\)

Vậy \(-3\le x\le4\)

câu a

x+(-7)=-20

x=-20-(-7)

x=-13

a)\(\left(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}\right).120+x:\frac{1}{3}=-4\)

\(\Rightarrow\left(\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}\right).120+x:\frac{1}{3}=-4\)

\(\Rightarrow\left(\frac{1}{24}-\frac{1}{30}\right).120+x:\frac{1}{3}=-4\)

\(\Rightarrow\frac{1}{120}.120+x:\frac{1}{3}=-4\)

\(\Rightarrow1+x:\frac{1}{3}=-4\)

\(\Rightarrow x:\frac{1}{3}=-4-1=-5\)

\(\Rightarrow x=-5.\frac{1}{3}=\frac{-5}{3}\)

b)\(1\frac{3}{5}+\left(\frac{\frac{2}{7}+\frac{2}{17}+\frac{2}{37}}{\frac{5}{7}+\frac{5}{17}+\frac{5}{37}}\right).x=\frac{16}{5}\)

\(\Rightarrow\frac{8}{5}+\left[\frac{2.\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}{5.\left(\frac{1}{7}+\frac{1}{17}+\frac{1}{37}\right)}\right].x=\frac{16}{5}\)

\(\Rightarrow\frac{8}{5}+\frac{2}{5}.x=\frac{16}{5}\)

\(\Rightarrow\frac{2}{5}.x=\frac{16}{5}-\frac{8}{5}=\frac{8}{5}\)

\(\Rightarrow x=\frac{8}{5}:\frac{2}{5}=\frac{8}{5}.\frac{5}{2}=\frac{8}{2}=4\)

\(\Rightarrow x=4\)

x=0, làm rồi nên biết đúng 100% đó

nhung to can cach giai

Vì |x^2-3x|>=0

|(x+1).(x-3)|>=0

Mà  |x^2-3x|+|(x+1).(x-3)|=0\(\Rightarrow\)

cả 2 vế đều bằng 0 rồi tìm x thế thôi

\(\frac{x-1}{5}+\frac{x-1}{7}+...+\frac{x-1}{37}=0=>\left(x-1\right).\left(\frac{1}{5}+\frac{1}{7}+...+\frac{1}{37}\right)=0\)

mà \(\frac{1}{5}+\frac{1}{7}+...+\frac{1}{37}>0\)

=> x-1 = 0

=> x = 1

Vậy x=1

đúng nha