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| Math Central | Quandaries & Queries |
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From Rita, a student: If a rock falls from a height of 20 meters on the planet Jupiter, its height H (a) What is the height of the rock when x = 1.2 seconds? (b) When is the height of the rock 15 meters? (c) When does the rock strike the ground? |
Hi Rita,
Part a) is fairly simple, just substitute 1.2 for x into the given equation. Part b) & c) can be solved using the same method. For example, in part b) H(x)=15 so if we substitute it into the original equation: 15= 20 - 13x2 which simplifies to 0= 5 - 13x2. The easiest way to find the time would be to solve for x using the quadratic formula.
For a review on using the quadratic formula check out this review.
Janice
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