We are given the relation between the height (in feet) and the distance (in miles) as follows:
y = sqrt(1.5x + (x/5280)^2).
We want to know the height (x) that makes the distance (y) = 10 miles
So, we will simply substitute in the above equation with y = 10 and calculate x as follows:
10 = sqrt(1.5x + (x/5280)^2)
we will square both sides to get rid of the root:
100 = 1.5x + (x/5280)^2
1.5x + (x/5280)^2 - 100 = 0
(x-66.11475)(x+7986.1147) = zero
either x = 66.11475 feet (accepted solution)
or x = -7986.1147 feet (rejected solution as no height is in negative)
Since the number is a fraction make a number line using fractions. The inequality sign includes being equal to, so add a solid dot on -5/2 and since x is less than that, draw an arrow pointing to the left.
See attached drawing.
For interval notation since x can be any number less than or equal to -5/2 it would be written as (-∞, -5/2]
