\(\frac{\left(x+1\right).x}{2}\)= 500500
(x+1).x = 500500.2=1001000
(x+1).x + 1001.1000
Vậy x = 1001 -1 =1000
Thử lại : nếu bạn muốn
\(1+2+3+...+x=500500\)
\(\Rightarrow\left(x-1\right):1+1.\frac{x+1}{2}=500500\)
\(\Rightarrow x.\frac{x+1}{2}=500500\)
\(\Rightarrow\)\(x.\left(x+1\right)=500500\cdot2\)
\(\Rightarrow\)\(x.\left(x+1\right)=1001000\)
\(\Rightarrow x.\left(x+1\right)=1000\cdot1001\)
\(\Rightarrow x=1000\)
1+2+3+.............+x=500500
[ (x-1):1+1] . (x+1) : 2 = 500500
x . (x +1 )= 500500 . 2
x . (x+1) = 1001000
x . ( x + 1) 1000 . 1001
Vậy x = 1000
