Given:
[tex]d=-gt^2+vt+c[/tex]To express v in terms of d, g, t, and c, take the following steps:
Step 1:
Subtract c from both sides
[tex]\begin{gathered} d-c=-gt^2+vt+c-c \\ \\ d-c=-gt^2+vt \end{gathered}[/tex]Step 2:
Divide through by t:
[tex]\begin{gathered} \frac{d}{t}-\frac{c}{t}=\frac{-gt^2}{t}+\frac{vt}{t} \\ \\ \\ \frac{d}{t}-\frac{c}{t}=-gt+v \end{gathered}[/tex]Step 3:
Add gt to both sides
[tex]\begin{gathered} \frac{d}{t}-\frac{c}{t}+gt=-gt+gt+v \\ \\ \frac{d}{t}-\frac{c}{t}+gt=v \\ \\ v=\frac{d}{t}-\frac{c}{t}+gt \end{gathered}[/tex]Therefore, the expression of v in terms of d, g, and c is:
[tex]v\text{ = }\frac{d}{t}-\frac{c}{t}+gt[/tex]ANSWER:
[tex]v=\frac{d}{t}-\frac{c}{t}+gt[/tex]