Answer:
It landed at a height of 14 feet
Step-by-step explanation:
Given
[tex]y = -\frac{1}{8}x^2 +4x[/tex] --- Path of a t-shirt
[tex]3y = 2x - 14[/tex] --- height of bleachers
Required
Height when t-shirts land in bleachers
[tex]3y = 2x - 14[/tex]
Make y the subject
[tex]y = \frac{2}{3}x - \frac{14}{3}[/tex]
Substitute [tex]y = \frac{2}{3}x - \frac{14}{3}[/tex] in [tex]y = -\frac{1}{8}x^2 +4x[/tex]
[tex]\frac{2}{3}x - \frac{14}{3} = -\frac{1}{8}x^2 +4x[/tex]
Multiply through by 24
[tex]16x- 112 = -3x^2 +96x[/tex]
Express as:
[tex]3x^2 + 16x -96x- 112 = 0[/tex]
[tex]3x^2 -80x- 112 = 0[/tex]
Using a calculator:
[tex]x = 28[/tex] or [tex]x = -\frac{4}{3}[/tex]
x can not be negative:
So:
[tex]x = 28[/tex]
Substitute [tex]x = 28[/tex] in [tex]y = -\frac{1}{8}x^2 +4x[/tex] to calculate the height it landed
[tex]y = -\frac{1}{8} * 28^2 + 4 * 28[/tex]
[tex]y = 14[/tex]
