# Math Help - proof using IVT

1. ## proof using IVT

My professor assigned this exercise and I'm not really sure how to get it started.

Suppose $f(a,b)<0$ and $f(c,d)>0$. Let $\phi : [0,1]\rightarrow R^2$ be determined by $\phi (t)=(1-t)(a,b)+t(c,d)$. Apply Bolzano's Intermediate Value Theorem to $g=f(\phi )$.

Any guidance would be appreciated.

2. Guidance with what...is there a question here?

3. I'm not sure how to use the Intermediate Value Theorem to $g=f(\phi )$.