To find the zeros, we set y=0 in the equation:
0 = -1/[(x+6)(x-18)]
This means that the numerator must be equal to zero, since a fraction is only zero when the numerator is zero. We can therefore solve:
x+6 = 0 or x-18 = 0
The first solution gives x=-6, and the second gives x=18. These are the two zeros of the equation, which correspond to the times when the rocket reaches ground level (assuming it takes off at x=0).
b) Use the equation to determine the zeros A group of students launches a model rocket from the top of a building. The
students have determined the equation y= − ;
(x + 6)(�x− 18) to describe the
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height of the rocket above ground level, �, in meters, at any time, �, in seconds.
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