Answer:
Hi there ,
to find the equation of the line
we have formula y-y1= m(x-x1) , where m is the slope .
Explanation:
y=3x
3x-y=0
slope of the line is given by -coef of x/coef of y
= -3/-1 = 3
as the line is perpendicular to 3x-y = 0
slope of required line (m) = -1/3
{using perpendicularity condition}
(x¹,y¹)=( 2,1)
equation of line = y-y1= m(x-x1)
= y-1 = -1/3(x-2)
or , 3y-3 = -x+2
or, x+3y=5 is the required equation
hope it helps...