View Full Version : PLease Help: graph 2x^2 - 3 and -1/2x^2

Quadratic Functions:

Graph f(x)=2x^2-3 and Graph f(x)= -1/2 x^2

please help me i have no clue what im doing. If you would please show me the steps and if you can answer. Well i know you can but if you dont mind please show me the answer.

:D Thankyou so much for just taking time to look at my post.

tkhunny

05-11-2006, 10:55 PM

Pick some values and substitute.

f(0) is usually good.

f(1) and f(-1) might be simple enough.

Are you familiar with how to graph single points?

not really please help me

tkhunny

05-11-2006, 11:04 PM

On a Cartesian Coordinate System (horizontal x-axis and vertical y-axis), you shoud be able to find any point. (1,1) is right 1 and up 1 - for example. You have had no introduction to this concept?

well to tell you the truth i am the kinda person who forgets if i dont practice it please help

tkhunny

05-12-2006, 12:13 AM

well to tell you the truth i am the kinda person who forgets if i dont practice it please helpMy attitude alarm just went off. You're going to have to do better than that. Read the other recent posts in this forum for just the sort of stuff you are asking.

ok i will thankyou for the advice

stapel

05-12-2006, 01:02 AM

Are you familiar with how to graph single points?

not really please help me

I'm afraid we can neither draw pictures nor teach courses here. If you haven't yet learned how to plot points, then that would be the first topic of study. Please review lessons along the lines of:

. . . . .WTAMU: Graphing Equations (http://www.wtamu.edu/academic/anns/mps/math/mathlab/int_algebra/int_alg_tut12_graph.htm)

. . . . .Math.com: The Coordinate Plane (http://www.math.com/school/subject2/lessons/S2U4L1GL.html)

. . . . .Introduction to the x,y-Plane (http://www.purplemath.com/modules/plane.htm)

Once you have learned how to plot points, you can try graphing quadratics.

. . . . .Ask Dr. Math: Graphing Quadratic Polynomials (http://mathforum.org/library/drmath/view/53235.html)

. . . . .WTAMU: Graphs of Quadratic Functions (http://www.wtamu.edu/academic/anns/mps/math/mathlab/col_algebra/col_alg_tut34_quadfun.htm)

. . . . .J. Wilson: Graphing Quadratic Functions (http://jwilson.coe.uga.edu/EMT668/EMAT6680.Folders/Barron/unit/Lesson%206/6.html)

. . . . .Graphing Quadratic Functions (http://www.purplemath.com/modules/grphquad.htm)

Once you have learned the basics of graphing quadratics, please attempt these exercises. If you get stuck, please reply explaining what you have tried and how far you have gotten.

Thank you.

Eliz.

i am extremly soory i do know how to plot coordinates (x,y) i was thinking of something else. Soory so please help thankyou

stapel

05-12-2006, 01:10 AM

i am extremly soory i do know how to plot coordinates (x,y) i was thinking of something else. Soory so please help thankyou

Okay, so if you can plot points, then, as was suggested earlier, do so.

Where are you stuck? Please reply with specifics. Thank you.

Eliz.

well how do i turn it into a coordinate. I know it sounds dumb but fractions always get me mixed up. please

stapel

05-12-2006, 02:29 PM

well how do i turn it into a coordinate.

How do you turn what into a coordinate? The x-value you plugged in is the x-coordinate, and the y-value you got out is the y-coordinate. There is no "turning" to do. You already have the values.

Eliz.

jsbeckton

05-12-2006, 05:30 PM

A graph is nothing more than a collection of points. A function implies that for every "x" value there is exactly one "y" value. Therefore you can start out with

x=0

and f(x) means y

now sub 0 in your equation everywhere there is an x:

\begin{array}{l}

f(x) = 2x^2 - 3 \\

y = 2x^2 - 3 \\

y = 2(0)^2 - 3 \\

y = 0 - 3 \\

y = - 3 \\

x = 0 \\

{\rm ordered pair}:(0, - 3) \\

{\rm Now plot that ordered pair on your graph}{\rm .} \\

{\rm Choose different values for x and do the same,} \\

{\rm you can then connect the dots and thats your graph}{\rm .} \\

\end{array}

\]

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