Question 308442
{{{4(sqrt(3a+4))=a+13}}}square everything
{{{4^2(sqrt(3a+4))^2=(a+13)^2}}}
{{{16(3a+4)=(a+13)(a+13)}}}distribute
{{{48a+64=a^2+26a+169}}} subtract 48a and 64 from both sides
{{{0=a^2-22a+105}}} -7 and -15 both multiply to get +105 and add to get -22
{{{0=(a-7)(a-15)}}}
{{{highlight(7=a)}}}{{{highlight(15=a)}}}