Graphing Functions??

Question

Graph the function. Describe the domain and range.

1) f(x)= 4x^2 + 16x + 13

2) f(x)= -3x^2 - 12x - 9

Answer 1

The domains of parabolas are both the same, always D: (-∞,∞)

For the range, I graphed them. The first one is [-3,∞) it goes to infinity because it opens up. The second one is the reverse, it opens down. (-∞,3]

You could also determine the range algebraically, using the formula

x coordinate of the vertex = -b/2a

Once you have the x coordinate of the vertex, plug it into the original equation to find the y coordinate. This is what is used in the ranges.