Question
How do I graph y = 2x squared -7?
Answers
Steve
Hard to believe your text has no examples of quadratic functions. In any case, excellent graphing help can be obtained at
http://rechneronline.de/function-graphs/
http://rechneronline.de/function-graphs/
Steve
In any case, graph it the same way you would any function. Pick a value for x, calculate y, and plot the point (x,y). Repeat until you get an idea of the shape of the curve.
Anonymous
Which values would be most adequate?
Anonymous
Which values should I use?
Steve
come on. Pick small values like -2,-1,0,1,2 where you can easily calculate y.
Just like you did when you were graphing lines in the beginning. You can use values like 2.83 or 5/17 or whatever, but it makes calculation a bit of a chore.
Just like you did when you were graphing lines in the beginning. You can use values like 2.83 or 5/17 or whatever, but it makes calculation a bit of a chore.
Steve
by this time you may know that parabolas have an axis of summetry. x-values equally distant from that axis produce the same y values.
For example, you know that 2x^2-7 is symmetric about the y-axis, because x^2 is always positive, whether x is positive or negative.
So, if you plot y for x=1, you automatically get y for x = -1.
For example, you know that 2x^2-7 is symmetric about the y-axis, because x^2 is always positive, whether x is positive or negative.
So, if you plot y for x=1, you automatically get y for x = -1.