Question

Find c such that f(x) -0.3x2-3x+c has a maximum value f(x) = -225.

Answer 1

we get that f(x) has a maximum when

$-0.6x-3=0\rightarrow x=-\frac{3}{0.6}=-5$

so we get that

$\begin{gathered} -0.3\cdot25-3\cdot-5+c=-225 \\ -7.5+15+c=-225 \\ 7.5+c=-225\rightarrow c=-225-7.5=-232.5 \end{gathered}$

so c=-232.5