A6. Determine the condition for $c$ so that the vertex of the quadratic parabola $f(x)=2 x^{2}+3 x+c$ lies in the III. quadrant.
(A) $c=0$
(B) $c>-1$
(C) $c>1 \frac{1}{8}$
(D) $c=1$
(E) $c<\frac{9}{8}$

## II. PART
A6. Let $f(x)=2 x^{2}+3 x+c=2\left(x^{2}+\frac{3}{2} x\right)+c=2\left(x+\frac{3}{4}\right)^{2}+c-\frac{9}{8}$. The vertex is at $x=-\frac{3}{4}$ and at that point $y=c-\frac{9}{8}$, so it will be in the III. quadrant if $c-\frac{9}{8}<0$, that is, $c<\frac{9}{8}$.

## II. PART