Problema Solution
Justin was interested in knowing the range of x-values for which the ball will be higher than 60 feet. He uses the path of the ball to write the following inequality:
-0.1x^2+8x-60>60
For which range of x-values is y greater than 60? Write your answer in the form a < x < b, and enter the values for a and b.
Answer provided by our tutors
Finding the endpoints for the range of 'x' is solved by setting the quadratic equation equal to 60:
-0.1x^2 + 8x - 60 = 60
x={20,60}
So the range could be expressed 20 < x < 60.
A graph of the equation visibly verifies that the parabolic trajectory is concave rather than convex (a convex parabolic equation would solve -inf>x U x < inf):