Question

[nguyen thu thao]

x.(x+1)=2+4+6+...+2500

Answer 1

[soyeon_Tiểu bàng giải]

x.(x + 1) = 2 + 4 + 6 + ... + 2500

x.(x + 1) = 2.(1 + 2 + 3 + ... + 1250)

x.(x + 1) = 2.(1 + 1250).1250 : 2

x.(x + 1) = 1250.1251

=> x = 1250

Vậy x = 1250 

Answer 2

[Sáng Nguyễn]

\(x\times\left(x+1\right)=2+4+6+...+2500\)
\(x\times\left(x+1\right)=2\times\left(1+2+3+...+1250\right)\)
\(x\times\left(x+1\right)=2\times\left(1+1250\right)\times1250\div2\)
\(x\times\left(x+1\right)=1250\times1251\)
\(\Rightarrow x=1250\)