`x+(x+1)+(x+2)+...+(x+30)=1240`

`=> (x + x + x + ... + x) + (1 + 2 + 3 +... + 30) = 1240`

`=> 31x + 465 = 1240`

`=> 31 x = 1240 - 465`

`⇒ 31x = 775`

`⇒ x = 775 : 31` 

`⇒ x = 25`

\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+30\right)=1240\\ \left(x+x+...+x\right)+\left(1+2+...+30\right)=1240\\ 31x+465=1240\\ 31x=1240-465\\ 31x=775\\ x=775:31\\ x=25\)

\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+30\right)=1240\)

\(\Leftrightarrow\left(x+x+...+x\right)+\left(1+2+...+30\right)=1240\)

\(\Leftrightarrow31x+465=1240\)

\(\Leftrightarrow x=25\)

\(...\Rightarrow x+x+\dfrac{x}{43}+\dfrac{x}{8}=14+148+\dfrac{10}{30}+\dfrac{5}{95}\)

\(\Rightarrow\left(1+1+\dfrac{1}{43}+\dfrac{1}{8}\right)x=162+\dfrac{1}{3}+\dfrac{1}{19}\)

\(\Rightarrow\left(\dfrac{2.43.8}{43.8}+\dfrac{1.8}{43.8}+\dfrac{1.43}{43.8}\right)x=\dfrac{162.3.19}{3.19}+\dfrac{1.19}{3.19}+\dfrac{1.3}{19.3}\)

\(\Rightarrow\left(\dfrac{688}{344}+\dfrac{8}{344}+\dfrac{43}{344}\right)x=\dfrac{9234}{57}+\dfrac{19}{57}+\dfrac{3}{57}\)

\(\Rightarrow\dfrac{739}{344}x=\dfrac{9256}{57}\)

\(\Rightarrow x=\dfrac{9256}{57}:\dfrac{739}{344}=\dfrac{9256}{57}.\dfrac{344}{739}=\dfrac{\text{3184064}}{\text{42123}}\)

x+30%.x=-1,3

=>x+\(\frac{3}{10}\).x=-1,3

=>x.(\(\frac{3}{10}+1\))=-1,3

=>x.1,3=-1,3

=>x=-1,3:1,3

=>x=-1

x+30%.x=-1,3

x+1/3.x=-1,3

x(1+1/3)=-13/10

x.4/3=-13/10

x= (-13/10) : (4/3)

x=-39/40

Ungr hộ mk nha

-39/40

Trả lời :

\(x+30\%\cdot x=-\frac{1}{3}\)

\(x+\frac{3}{10}\cdot x=-\frac{1}{3}\)

\(x\left(1+\frac{3}{10}\right)=-\frac{1}{3}\)

\(\frac{13}{10}x=-\frac{1}{3}\)

\(x=-\frac{1}{3}:\frac{13}{10}\)

\(x=-\frac{10}{39}\)

Vậy \(x=-\frac{10}{39}\)

Hok tốt

-Ken-

\(x+30\%x=-1,3\)

\(\Leftrightarrow1x+\frac{30}{100}x=-1,3\)

\(\Leftrightarrow\frac{10}{10}x+\frac{3}{10}x=-1,3\)

\(\Leftrightarrow x\left(\frac{10}{10}+\frac{3}{10}\right)=-1,3\)

\(\Leftrightarrow\frac{13}{10}x=\frac{-13}{10}\)

\(\Leftrightarrow x=\frac{-13}{10}\div\frac{13}{10}\)

\(\Leftrightarrow x=\frac{-13}{10}\times\frac{10}{13}\)

\(\Leftrightarrow x=-1\)

\(x+30\%\cdot x=-1,3\)

\(100\%\cdot x+30\%\cdot x=-1,3\)

\(x\cdot\left(100\%+30\%\right)=-1,3\)

\(x.130\%=-1,3\)

\(x=-1,3:130\%\)

\(x=-1\)

x=1 nhớ đúng cho hai mình nha

khi nào cần giúp cho

x+3/10x=-1,3

x*(3/10+1)=-1,3

x=-1

x=1