Question 1194739
{{{T=2pi*sqrt(l/g)}}}

{{{T/(2pi)=sqrt(l/g)}}}........square both sides

{{{(T/(2pi))^2=(sqrt(l/g))^2}}}

{{{T^2/(4pi^2)=l/g}}}......cross multiply

{{{gT^2=(4pi^2)*l}}}

{{{g=(4pi^2*l)/T^2}}}

{{{g=(2pi/T)^2*l}}}