Question

A plane is descending into the airport. After 5 minutes it is at a height of 6500 feet. After 7 minutes it is at a height of 5900 feet. Write an equation to model its height after t minutes. When will it land assuming the airport is at 0 feet.

Answer 1

Let's assume

height of plane  in feet =h

time in minutes =t

we are given

A plane is descending into the airport. After 5 minutes it is at a height of 6500 feet

so, we get one point as (5,6500)

After 7 minutes it is at a height of 5900 feet

so, we get another point as (7,5900)

we can use point slope form of line

$y-y_1=m(x-x_1)$

points as

(5,6500)

x1=5, y1=6500

(7,5900)

x2=7 , y2=5900

Calculation of slope(m):

$m=\frac{y_2-y_1}{x_2-x_1}$

now, we can plug values

$m=\frac{5900-6500}{7-5}$

$m=-300$

Equation of line:

we can use formula

$y-y_1=m(x-x_1)$

we can plug values

$h-6500=-300(t-5)$

$h=-300t+8000$

Time of landing:

we can set h=0

and then we can solve for t

$h=-300t+8000=0$

$t=\frac{80}{3}min$..............Answer