Math Problem Statement
A ball is launched at 42 feet per second. The height of the ball (in feet) is given by the equation h=-16t+48t+6, where T is the time (in seconds) since the ball was launched. For how many seconds is the ball at or above a height of 38 feet?
Solution
To determine how long the ball is at or above a height of 38 feet, we start with the height equation given:
We need to find the times when . Setting up the inequality:
Subtracting 38 from both sides gives:
Next, we simplify this equation:
Dividing through by -16 (and reversing the inequality):
Now we can factor this quadratic:
To find the critical points, we set each factor to zero:
The quadratic will be zero at and . We can analyze the intervals around these points to find where the expression is less than or equal to zero.
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For : Choose :
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For : Choose :
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For : Choose :
The quadratic is negative or zero in the interval:
Thus, the ball is at or above a height of 38 feet for:
Summary
The ball is at or above a height of 38 feet for 1 second.
Would you like any further details or clarifications? Here are some related questions you might consider:
- What is the maximum height reached by the ball?
- How long does it take for the ball to reach its maximum height?
- What is the time when the ball first hits the ground?
- How does the launch speed affect the time the ball is above a certain height?
- What would be the height of the ball after 3 seconds?
Tip: When analyzing quadratic functions, consider the vertex and intercepts to understand the shape and behavior of the graph.
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Math Problem Analysis
Mathematical Concepts
Algebra
Quadratic Functions
Inequalities
Formulas
h(t) = -16t^2 + 48t + 6
Quadratic inequality solution
Theorems
Factoring quadratics
Interval testing for inequalities
Suitable Grade Level
Grades 9-11
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