Question

x= 1+2+3+.....+225
x=?

Answer 1

x=[(1+225)*225]:2
x=(226*225):2
x=(226:2)*225
x=113*225
x=25425
Sper ca e bun

Answer 2

$\displaystyle x=1+2+3+...+225 \\ \\ x= \frac{225(225+1)}{2} \\ \\ x= \frac{225 \cdot 226}{2} \\ \\ x= \frac{50850}{2} \\ \\ \boxed{x=25425}$