Question 976779
{{{(3r+1)^2+(r+2)^2=65}}}

simplifies to

{{{(9r^2+6r+1)+(r^2+4r+4)=65}}}

{{{10r^2+10r+5=65}}}

Now divide through by 5

{{{2r^2+2r+1=13}}}

{{{2r^2+2r-12=0}}}

Divide by 2

{{{r^2+r-6=0}}}

{{{(r-2)(r+3)}}}

r=2 or r= -3

No need to multiply to 600