Question 392420
{{{sqrt(y+20) = y}}}
Square both sides:
{{{y + 20 = y^2}}},
==> {{{0 = y^2 - y - 20}}}
==> (y-5)(y+4) = 0 ==> y = 5, -4.
Y = 5 satisfies the original equation, while y = -4 does not.
Therefore the final answer is only y = 5.