Laila purchased a prepaid phone card for $25 . Long distance calls cost 24 cents a minute using this card. Laila used her card o
1 answer:
Answer:
The call lasted for 47 minutes.
Step-by-step explanation:
It is given that:
Value of prepaid card = $25
Cost per minute of long distance call = 24 cents = $0.24
Remaining credit = $13.72
Let,
x be the number of minutes
y be the remaining amount
y = 25 - 0.24x
13.72 = 25 - 0.24x
0.24x = 25 - 13.72
0.24x = 11.28
Dividing both sides by 0.24
Therefore,
The call lasted for 47 minutes.
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Answer:
The rocket hits the ground at a time of 11.59 seconds.
Step-by-step explanation:
The height of the rocket, after x seconds, is given by the following equation:
It hits the ground when , so we have to find x for which
, which is a quadratic equation.
Finding the roots of a quadratic equation:
Given a second order polynomial expressed by the following equation:
.
This polynomial has roots such that
, given by the following formulas:
In this question:
So
Since time is a positive measure, the rocket hits the ground at a time of 11.59 seconds.