Question

\(x\)+2x\(x\)+3x\(x\)+....+10x\(x\)=8250

Answer 1

Lời giải:
$x+2\times x+3\times x+...+10\times x=8250$
$x\times (1+2+3+...+10)=8250$

$x\times \frac{10\times 11}{2}=8250$

$x\times 55=8250$

$x=8250:55=150$