Page 77 - Math Course 3 (Book 1)

Quadratic and Cubic Equations

t y = – x 3 (x, y)
600 2
(–2) 3 = 4
–
500 –2 2 (–2, 4)
Distance (ft) 400 –1 – (–1) 3 3 = 1 (–1, )
1
2
2
2
300
(0)
200 0 – 2 = 0 (0, 0)
1
1 – (1) 3 = – 1 (1, – )
100 2 2 2
2 – (2) 3 = –4 (2, –4)
0 1 2 3 4 5 6 t 2
Time (s)
3
Graph y = 2x + 2.
The graph shows the distance the skydiver falls
over a period of about 6 seconds. The distance
at 0 seconds is 0 feet, so the skydiver had not
yet left the airplane. As the time increases the
distance also increases.

Unreasonable values for x would be any negative
numbers because time cannot be negative.
Negative values for y are also unreasonable
because the skydiver does not reverse direction.

The distance the skydiver falls
Answer after 4.5 seconds is about 320
feet.
3
x y = 2x + 2 (x, y)
Graph Cubic Functions –1.5 2(–1.5) + 2 = –4.75 (–2, 4)
3
Examples –1 2(–1) + 2 = 0 (–1, 0)
3

3
x 3 0 2(0) + 2 = 2 (0, 2)
Graph y = –
2
1 2(1) + 2 = 4 (1, –4)
3

1.5 2(1.5) + 2 = 8.75 (1.5, 8.75)
3

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