paulo1913 Posted October 27, 2007 Share Posted October 27, 2007 How do I graph a parabolic equation on a graph? for example 2x^2-3? Link to comment Share on other sites More sharing options...
ghstofmaxwll Posted October 27, 2007 Share Posted October 27, 2007 Do a table of plots. So plug 1 into "x" then 2 into "x" and so on and so on.... Then plot these x and y values as coordinates on an xy graph. Then you will have a parabola, then just shift every point down 3 and this 2nd parabola will be "f(x)=2x^2-3"(your equation you were on about). Link to comment Share on other sites More sharing options...
ydoaPs Posted October 27, 2007 Share Posted October 27, 2007 That isn't a parabola; it's an expression. However, y=2x2-3 is a function, so it can be graphed(and it is a parabola). Make a chart of values with two columns(one side is x, the other y). Choose some x values and then plug them into the equation to get the y values. Some values you definitely should chart are the x-intercept(where y=0) and the y-intercept(where x=0). Link to comment Share on other sites More sharing options...
ghstofmaxwll Posted October 27, 2007 Share Posted October 27, 2007 f(x)=2x^2-3 is y=2x^2-3, dilburt. Link to comment Share on other sites More sharing options...
ydoaPs Posted October 27, 2007 Share Posted October 27, 2007 f(x)=2x^2-3 is y=2x^2-3, dilburt. I was responding to the OP in which an expression was to be used as a function. Link to comment Share on other sites More sharing options...
ghstofmaxwll Posted October 27, 2007 Share Posted October 27, 2007 I was responding to the OP in which an expression was to be used as a function. Oh sorry, I though you were picking at me for having the foresight to know what he really meant. Link to comment Share on other sites More sharing options...
martianxx Posted November 8, 2007 Share Posted November 8, 2007 If i were doing it i would say what y = when x=0 y would = -3 then what x is when y = 0. You have to use the quadratic formula x = -b (+/-) Root of b^2 - 4ac all divided by 2a for this particular equation a = 2 b = 0 and c = -3 you can work out the maximum/minimum via differentiation but you can get a prety good outline of the graph from working out the y and x values. p.s Remember when you square root in the formula it gives two answers still when b = 0. Link to comment Share on other sites More sharing options...
the tree Posted November 11, 2007 Share Posted November 11, 2007 It largely depends on what level of accuracy your looking for: a sketch to show you understand the concepts or a plotting to actually be useful? Martianxx's and Ghstofmaxwll's approaches are useful for each occasion respectively. Link to comment Share on other sites More sharing options...
ghstofmaxwll Posted November 12, 2007 Share Posted November 12, 2007 p.s Remember when you square root in the formula it gives two answers still when b = 0. I need that tattooed on a place that I always pay attention to. Link to comment Share on other sites More sharing options...
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