Question

the altitude of 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?

Answer 1

If our equation is $a = 3400t + 600$, and we have a target altitude of $21,000$, we just need to plug that in for $a$.

$21,000 = 3,400t + 600$. Now subtract $600$ from both sides.

$20,400 = 3,400t$. now divide both sides by $3,400$.

$6 = t$.

We get that our answer is at 6 minutes we get an altitude of 21,000 feet!