please help? what is the equation in standard form, of a parabola that contains the following points?
(-2,18), (0,4), (4,24)

y=-2x^2+3x-4
y=2x^2-3x+4
y=-3x^2+2x+4
y=_4x^2-3x-2

Question

please help?  what is the equation in standard form, of a parabola that contains the following points?
(-2,18), (0,4), (4,24)

y=-2x^2+3x-4
y=2x^2-3x+4
y=-3x^2+2x+4
y=_4x^2-3x-2

anonymous · Answer

the last one should be -4, not _4

anonymous · Answer

anybody?

tkhunny · Answer

Have you considered substitution and the solution of the resulting simultaneous equations?

anonymous · Answer

how would I do that?

tkhunny · Answer

From the given choices, it's pretty clear that the equation will look like this:

y = ax^2 + bx + c

Right?

anonymous · Answer

oh wait I just found the example in my book. lets see here...

tkhunny · Answer

Don't miss the fact that the GAVE US the y-intercept.  This leads immediately to:

a(0)^2 + b(0) + c = 4

c = 4

Now, we have this:

y = ax^2 + bx + 4

And two more points to find a and b.

anonymous · Answer

I believe it would be y=2x^2-3x+4, right?

tkhunny · Answer

Did you just substitute the points into the given equations?

BTW  Once we have c = 4, we can discard the first and the last.

anonymous · Answer

im solving it how it showed me in the book on paper, and the answer I posted is what I got after substituting the points into the equation.

tkhunny · Answer

Unique answers don't care how you find them.  Good work.

anonymous · Answer

sweet. thanks for your help