$T = 2\pi\sqrt{\dfrac{L}{g}}$ Rearrange the formula to make g the subject. Answer g = ...

1. Isolate the square root term.

$T=2\pi\sqrt{\dfrac{L}{g}}$

Divide both sides by $2\pi$:

$\frac{T}{2\pi}=\sqrt{\frac{L}{g}}$

2. Remove the square root by squaring both sides.

$\left(\frac{T}{2\pi}\right)^2=\frac{L}{g}$

So

$\frac{T^2}{4\pi^2}=\frac{L}{g}$

3. Rearrange the fractional equation to make $g$ the subject.

$\frac{T^2}{4\pi^2}=\frac{L}{g}$

Cross-multiply:

$gT^2=4\pi^2L$

Divide by $T^2$:

$g=\frac{4\pi^2L}{T^2}$