Graphing

I have a question, y=x^2+3x+4, how would I graph it?
Importing some values into x? Or this is regarding some knowledge in probabolas? In addition, anyone know how to solve 3^y=9?

Quote:

---

Originally posted by prog_tom
I have a question, y=x^2+3x+4, how would I graph it?
Importing some values into x? Or this is regarding some knowledge in probabolas? In addition, anyone know how to solve 3^y=9?

---

Its been a while since I've played with logs, so I could be wrong, but...
I believe log(a^b) = bloga So...

Logging both sides,
log(3^y) = log(9)
y*log(3) = log(9)
y = log(9)/log(3)
and so, according to my calculator,
y = 2

Which is logical, since 3 squared is 9.

Anyways, graphing via progie is best done by plugging incrimental values of x, and plotting the resultant y in relation to x.

You CAN go to complexity, by illustrating maxima, minima, and all the various props of your equation, but to display the curve properly, its best to use actual values, instead of approximations.

-Lou

Of course, with a calculator everything is possible, and yes, I know in case of 3^y=9, y must be 2, but is there anyway to solve 3^y=9?

:confused:
y = log(9)/log(3)
:confused:

You can do this without Logs. You just need to know the rules of indicies, and equate powers. For example, you have 3^y = 9, which is the same as 3^y = 9^1. Now you know that the square root of 9 is 3, so you can write the expression as 3^y = 3^2. Equate powers, and you have y = 2.

I still say use graphmatica from www.graphmatica.com instead of programming your own grapher.