Answer: D
Step-by-step explanation:
f²i = -f²t + h
+f²t +f²t
f²i + f²t = h
f²(i + t) = h
[tex]\frac{f^{2}(i + t) }{i + t} = \frac{h}{i + t}[/tex]
[tex]f^{2}= \frac{h}{i + t}[/tex]
[tex]\sqrt{f^{2} } = \sqrt{\frac{h}{i + t} }[/tex]
f = +/- [tex]{\sqrt{\frac{h}{i + t} }[/tex]
