help with graphing?

Question

I'm really rusty on my basic math skills how would I graph the following equation? Thank you in advance for all your help!

y = 7 - 6x - x^2

Answer 1

First get some graph paper.Draw an x-y coordinate system (if you jut have regular paper then do the drawing as as best you can).

First note some things about the equation. Since there is basically a "y" equal "x^2" this will be a parabola. And since there is a minus sign in front of the x^2 it will open downwards (note that as x gets larger and larger, y gets larger and larger and also that it is less than 0).

If you do not know calculus then skip this little bit.
If you know calculus you can get the maximum point by taking the derivative and setting it equal to 0.

dy/dx = -6 -2x and x =-3

and the graph will be symmetric about the line x=-3
END of calculus stuff

Them just make a list of the points to plot by picking x values and using the formula to calculate y.

x = 0 so y = 7
x = 1 so y = 0
x = -1 so y = 12
x = 2 so y = -9
x= -2 so y = 1
x = 3 so y =-20
x = -3 so y = 16

and so on and on. The plot the points and draw a smooth line through them

Answer 2

Ok so this is how I see it... A bar graph is best used when you are making a few comparisons with specific numerical values. However, a bar graph becomes a bit cumbersome if you have too many values or are making too many comparisons. Ex. Max Height of a peach tree vs Max Height of Apple tree, etc. A line graph is best used when comparing a lot of data points. Line graphs are wonderful in showing changes over time. Ex. Changes in height of a peach tree from 2000 to 2009 A pie graph ( circle graph) is the easiest in that each slice represents a piece of the whole. So if your messing with a percentage than Pie Graph is best. Ex. A portion of a total amount of peaches given to various individuals. Hope this helps a little. You get the feel for it the more you work with the various graphs.