Question 877609
The slope of {{{y = (1/2)x}}} is {{{1/2}}}


Flip the fraction: {{{1/2}}} ----> {{{2/1 = 2}}}
Flip the sign: {{{2}}} ----> {{{-2}}}


The perpendicular slope is {{{-2}}}. So {{{m = -2}}}


-------------------------------------------------------


{{{y = mx+b}}}



{{{y = -2x+b}}} Plug in {{{m =-2}}}



{{{1 = -2(2)+b}}} Plug in (x,y) = (2,1). Solve for b.



{{{1 = -4+b}}}



{{{1+4 = b}}}



{{{5 = b}}}



{{{b = 5}}}



-------------------------------------------------------



Since {{{m = -2}}} and {{{b = 5}}}, the equation {{{y = mx+b}}} turns into {{{y = -2x+5}}}


The perpendicular equation is {{{y = -2x+5}}}