# Let f ( x ) = x 2 </msup> + x &#x2212;<!-- − --> 6 .

Let $f\left(x\right)={x}^{2}+x-6$.
a. Write down the $y$-intercept of the graph of $f$.
how do we figure this out? I know $f\left(x\right)$ means $y$, so do we use the quadratic formula? ${x}^{2}+x-6$.
b. Solve $f\left(x\right)=0$.
We plug $0$ into the $x$’s in the original formula, right?
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Julius Johnston
When you're being asked for the $y$-intercept of the graph, you're being asked where your graph crosses the $y$ axis - i.e. where $x=0$. This is what you need for part $a\right)$.
For part $b\right)$, you're being asked where the graph crosses the $x$ axis, and this is where $y=0$ or alternatively where $f\left(x\right)=0$. As such, you need to solve the equation $f\left(x\right)=0$, for $x$.