Question

tìm x biết

(x+1) + (x+2) + ... +(x+20)=930

Answer 1

\(\left(x+1\right)+\left(x+2\right)+...\left(x+20\right)=930\)

\(\Rightarrow\left(x+x+...+x\right)+\left(1+2+...+20\right)=930\)

\(\Leftrightarrow20x+\left(\frac{\left(20+1\right).20}{2}\right)=930\)

\(\Leftrightarrow20x+210=930\)

\(\Leftrightarrow20x=930-210=720\)

\(\Leftrightarrow x=\frac{720}{20}=36\)

Vậy : \(x=36\)

Answer 2

\(\left(x+1\right)+\left(x+2\right)+...+\left(x+20\right)=930\)

\(\Rightarrow\left(x+x+..+x\right)+\left(1+2+...+20\right)=930\)

\(\Rightarrow20x+210=930\)

\(\Rightarrow20x=720\Rightarrow x=36\)

Answer 3

đáp số 

36 

hok tốt

Answer 4

trả lời x=36