Question

pls try to find (g) .............................

Answer 1

T=2π√(l/g)
T/2π=√(l/g)
Square both sides
T^2/4(π^2)=l/g
g=l/[T^2/4(π^2)]
g=4l(π^2)/T^2
To simplify more you can also write as
g=[{2π√l}/T]^2