Question 368794
From {{{sqrt(7x+36)=x+4}}}
let us square both sides and get
{{{7x + 36 = x^2 + 8x + 16}}}
Now collect terms and get
{{{x^2 + x - 20 = 0}}}  (Notice I flipped it)
Now factor and solve
{{{(x + 5)(x - 4) = 0}}}
and
x = -5 or x = 4
For problems involving roots, YOU HAVE TO CHECK solutions.
Notice x = 4 works fine but x = -5 does not.