Question

Tìm x biết x + 2x + 3x + ⋯ + 10x = -165. Trả lời: x =

Answer 1

x+2x+3x+...+10x=-165

=(1+2+3+4+...+10)x=-165

=55x=-165

\(\Rightarrow\)x=-165:55=-3

Answer 2

x+2x+3x+...+10x=-165

=>1x+2x+3x+...+10x=-165

=>(1+2+3+4+...+10)x=-165

55x=-165

x=-165:55

x=-3