Question

A remote-control airplane descends at a rate of 2 feet per second. After 3 seconds it is 67 feet above the ground. Write the equation in point-slope form that models the situation. Then, find the height of the plane after 8 seconds.

Answer 1

A] A remote-control airplane descends at a rate of 2 feet per second. After 3 seconds it is 67 feet above the ground. 
the point slope equation will be given as follows:
y-y1=m(x-x1)
where:
slope,m=2 ft/sec
(x1,y1)=(3,67)
thus plugging in the values in the formula, we obtain the point slope equation as follow:
y-67=2(x-3)

Answer:
y-67=2(x-3)

b]The height of the plane after 8 seconds will be:
x=8 sec
but:
y-67=2(x-3)
substituting x=8 we get:
y-67=2(8-3)
y-67=2(5)
y=10+67
y=77
thus the height after 8 seconds is 77 ft