Question

Tìm x , biết:

1+2+3+4+...+x=500500

Answer 1

1+2+3+4+...+x=500500

\(\frac{\left(x+1\right).x}{2}=500500\)

\(\left(x+1\right).x=1001000\)

\(1001.1000=100100\)

Vậy x = 1000

Answer 2

1+2+3+4+...+X = 500500

( X + 1 ) x X : 2 = 500500

( X + 1) x X       = 500500 x 2

( X + 1) x X       = 1001000

1000 x ( 1000+ 1) = 1001000

Vậy x = 1000

Answer 3

Theo công thức ta có:

\(\frac{x\left(x+1\right)}{2}=500500\Leftrightarrow x^2+x-1001000=0\Leftrightarrow x=1000\)

Answer 4

\(1+2+3+4+...+x=500500\)

\(\left(1+x\right).x\div2=500500\)

\(\left(1+x\right).x=500500.2\)

\(\left(1+x\right).x=1001000\)

\(\left(1+x\right).x=1001.1000\)

\(\Rightarrow x=1000\)

Answer 5

 1 + 2 + 3 + 4 + ... + x = 500500 

(x + 1) . x  : 2 = 500500

(x + 1) . x = 500500 x 2

=(x + 1) . x = 1001000

 = 1001 x 1000

= > x là 1000