Question

[Tran inh Toan]

Tìm x biết:

2+4+6+8+...+2x = 10100

Nho cac ban huong dan giai giup bai nay

Answer 1

[Mạc Thu Hà]

A=2(1+2+3+.........+x)=10100

suy ra 1+2+3+.................+x=5050

\(\frac{x\left(x+1\right)}{2}\)=5050 \(\Rightarrow\)x²+x=10100\(\Rightarrow\)x²+x-10100=0\(\Rightarrow\)x=100 hoac x=-101 ma x>0 nen x=100