How do you find two quadratic function one that opens up and one that opens downward whose graphs have intercepts (-5,0), (5,0)?

1 Answer
Jan 7, 2017

Many answers possible:
Ex. y = 2x^2 - 50y=2x250 opens up and y = -24x^2 + 600y=24x2+600 opens down

Explanation:

The form y = c(x - a)(x - b)y=c(xa)(xb) represents intercept form, where cc is a constant. If c > 0c>0, the parabola opens up. If c < 0c<0, the parabola opens down.

So, we can pick absolutely any value of cc that is below 00 if we want the parabola to open down and absolutely any value of cc that is above 00 if we want the parabola to open up.

Thus, we can have equations:

y = 2(x - 5)(x + 5)y=2(x5)(x+5)
y = 2(x^2 - 25)y=2(x225)
y = 2x^2 - 50y=2x250 opens up

AND

y = -24(x -5)(x + 5)y=24(x5)(x+5)
y = -24(x^2 - 25)y=24(x225)
y = -24x^2 + 600y=24x2+600 opens downwards

Hopefully this helps!