Answer:
C. [tex]c = \frac{-7+-\sqrt{129} }{8}[/tex]
Step-by-step explanation:
Before we start, you can think of the variable "c," as x.
The quadratic formula/equation is:
[tex]x = \frac{-b+-\sqrt{b^2-4ac} }{2a}[/tex]
The setup is:
[tex]ax^2+bx+c=0[/tex]
[tex]4c^2+7c-5=0[/tex]
Plug in the numbers accordingly to the letter associated, like so:
[tex]x = \frac{-7+-\sqrt{7^2-4(4)(-5)} }{2(4)}[/tex]
[tex]x = \frac{-7+-\sqrt{49+80} }{8}[/tex]
[tex]x = \frac{-7+-\sqrt{129} }{8}[/tex]
