Question 448614
{{{sqrt(5x+39)=x+3}}}
start by squaring both sides to get:
{{{5x+39 = (x+3)^2}}}
{{{5x+39 = (x+3)(x+3)}}}
FOIL the right side:
{{{5x+39 = x^2+6x+9}}}
{{{39 = x^2+x+9}}}
{{{0 = x^2+x-30}}}
factoring the right:
{{{0 = (x+6)(x-5)}}}
x = {-6, 5}