# graphing

• May 18th 2011, 08:51 PM
homerb
graphing
how do i do it to graph this in a calculator x= y^2 + 2y + 1
• May 18th 2011, 08:54 PM
TKHunny
Don't laugh.

Graph this: y = x^2 + x + 1

Then turn your calculator 1/4 turn clockwise. :-)
• May 18th 2011, 09:01 PM
homerb
it is funny, but there is not another way to do it? like solving for y
• May 18th 2011, 09:03 PM
TKHunny
You can solve for y, but you may not be happy with the results. You should get TWO different pieces. It is not a "function", so it takes a bit more effort.

I'd just turn the calculator. Don't you think your classmates would get a hoot out of it? Maybe your teacher has a sense of humor? It demonstrates a knowledge of reflection across the line x = y. Don't you want to be the first on in your class to claim that knowledge?
• May 18th 2011, 11:21 PM
jgv115
Hahaha you were probably told to graph the inverse of $\displaystyle y =x^2 +x +1$ as TKHunny said.

You can't take the inverse of a quadratic in polynomial form. You have to complete the square and put it into Turning Point form then swap x and y and solve for y.
• May 19th 2011, 04:25 AM
TKHunny
Okay, technically, you should grab your calculator by the upper right and lower left corners and flip it over, but in this case the 90º rotation is a good substitute.
• May 19th 2011, 05:43 AM
mr fantastic
Quote:

Originally Posted by homerb
how do i do it to graph this in a calculator x= y^2 + 2y + 1

(Otherwise: $\displaystyle x = (y + 1)^2 + 1 \Rightarrow \pm \sqrt{x - 1} = y + 1 \Rightarrow y = ....$, which is of a form that can be eneterd into a graphics calculator.)