# Math Help - Plotting Functions

1. ## Plotting Functions

Thank you to all who answered my last thread. This will be my last question of the night. Once again, I am having trouble with the steps here.

It's asking me to plot the functions:

f(X)=x^2+2x-3 for -4 [lesser or equal to sign]x[lesser or equal to sign]2

I know how to plot once I get the points, but I just need help getting the points. :/

Thanks!

2. ## Re: Plotting Functions

You can just plot $f(x)=x^2+2x-3 = (x+3)(x-1)$ and discard the function outside the given interval.

3. ## Re: Plotting Functions

Originally Posted by annon25
Thank you to all who answered my last thread. This will be my last question of the night. Once again, I am having trouble with the steps here.

It's asking me to plot the functions:

f(X)=x^2+2x-3 for -4 [lesser or equal to sign]x[lesser or equal to sign]2

I know how to plot once I get the points, but I just need help getting the points. :/

Thanks!
In order to plot function you have to find zero's and point of local minimum :

a) to find zero's you have to solve following :

$x_{1,2}=\frac{-2 \pm \sqrt {4+12}}{2}$

b) to find point of local minimum you have to solve following :

$f'(x)=0 \Rightarrow f'(x)=2x_{min}+2=0$ and

$y_{min}=x_{min}^2+2x_{min}-3$