Question 1169138
{{{sin(2x) − sin(x)}}}

since {{{sin(2x)=sin(x+x)}}}, use Angle-Sum  Identity

{{{sin(alpha + beta) = sin(alpha) cos(beta) + cos(alpha) sin(beta)}}} where {{{alpha=x}}} and {{{beta=x}}}

 {{{sin(x + x) = sin(x) cos(x) + cos(x) sin(x)=2sin(x)cos(x)}}}

then you have

{{{2sin(x)cos(x)-sin(x)}}}......factor out common {{{sin(x)}}}

{{{sin(x)(2cos(x)-1)}}}=>expression is equivalent to {{{sin(2x)-sin(x)}}}