Question 317301
{{{a/4=9/a}}} Start with the given equation.



{{{a*a=9*4}}} Cross multiply.



{{{a^2=36}}} Multiply.



{{{a=""+-sqrt(36)}}} Take the square root of both sides.



{{{a=sqrt(36)}}} or {{{a=-sqrt(36)}}} Break up the plus/minus.



{{{a=6}}} or {{{a=-6}}} Take the square root of 36 to get 6.



So the solutions are {{{a=6}}} or {{{a=-6}}}