ANSWER
[tex]g = - \frac{5}{2} \: or \: g = \frac{5}{2} [/tex]
EXPLANATION
The given equation is
[tex]4 {g}^{2} = 25[/tex]
Divide both sides by 4.
[tex]{g}^{2} = \frac{25}{4} [/tex]
Take the square root of both sides:
[tex]g = \pm \sqrt{ \frac{25}{4} } [/tex]
[tex]g = \pm \frac{5}{2} [/tex]
Split the plus or minus sign:
[tex]g = - \frac{5}{2} \: or \: g = \frac{5}{2} [/tex]