How to graph a parabola y=12(x+1)(x5)?

1 Answer
May 12, 2015

From the formula y=(12)(x+1)(x5), we can tell several things:

The coefficient of x2 is positive, so the parabola is upright, shaped a bit like a U.

The parabola crosses the x-axis where y=0, when x=1 and x=5.

The vertex of the parabola will have an x coordinate exactly between these two values x=1+52=2.

Substituting x=2 into the formula, we get

y=(12)(2+1)(25)=(12)3(3)=92=4.5

So the vertex of the parabola is at (2,4.5).

If you want to know any more points through which the parabola passes, choose an x coordinate and substitute it into the formula to get the corresponding y value.