Bài tìm x

E

eye_smile

PT \Leftrightarrow $100x+(1+2+3+...+100)=205550$
\Leftrightarrow $100x+5050=205550$
\Leftrightarrow $100x=200500$
\Leftrightarrow $x=2005$
 
T

tranhainam1801

(x+1)+(x+2)+(x+3)+(x+4)+...+(x+100)=205550
x.100+(1+2+3+...+100)=205550
x.10+ [TEX]\frac{(100+1).100}{2}[/TEX]=205550
....................................​
 
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