The altitude a (in feet) of a plane t minutes after liftoff is given by a=3400t+600. How many minutes after liftoff is the plane at an altitude of 21,000 feet?
+590 So I guess time is in minutes.
The question says: How many minutes after liftoff is the plane at an altitude of 21,000 feet?
So... in the equation a=3400t+600, we plug in 21,000 for a. Because we have to find 't' when 'a' is 21,000.
That gives us 21,000 = 3400t+600.
Subtract 600 to both sides to get 20,400 = 3400t
Divide both sides by 3,400 and you get 6 = t.
So it takes 6 minutes for the plane to be at an altitude of 21,000.
6 minutes.
+590 So I guess time is in minutes.
The question says: How many minutes after liftoff is the plane at an altitude of 21,000 feet?
So... in the equation a=3400t+600, we plug in 21,000 for a. Because we have to find 't' when 'a' is 21,000.
That gives us 21,000 = 3400t+600.
Subtract 600 to both sides to get 20,400 = 3400t
Divide both sides by 3,400 and you get 6 = t.
So it takes 6 minutes for the plane to be at an altitude of 21,000.
6 minutes.
