$[0\mathrm{.}5/1$ Points$]$

Cost, revenue, and profit are in dollars and $x$ is the number of units.

If the marginal cost for a product is $\frac{?}{\text{b}\text{a}\text{r}}(MC)=8+6\sqrt[\phantom{2}]{2x+9}$ and the total cost of producing $20$ units is $$7,000,$ find the total cost function.

$C(x)$

Find the fixed costs $($in dollars$).$