Question 512029
{{{ -28=-4sqrt (r+8)}}}


{{{ (-28)^2=(-4sqrt (r+8))^2}}}


{{{ 784=16(r+8)}}}


{{{ 784/16=r+8}}}


{{{ 49=r+8}}}


{{{ 49-8=r}}}


{{{ 41=r}}}


{{{ r=41}}}