Question

x+2x+3x+4x+...+100x=-213

Tìm x nha

Answer 1

\(\Leftrightarrow x\left(1+2+3+...+100\right)=-213\)

\(\Leftrightarrow x\cdot\frac{101\cdot100}{2}=-213\)

\(\Leftrightarrow5050x=-213\)

\(\Leftrightarrow x=-\frac{213}{5050}\)

Answer 2

x+2x+3x+...+100x=-213

x.(1+2+3+...+100)=-213

x[100.(100+1)/2]=-213

x.5050=-213

x=-213/5050

vậy x=-213/5050