The altitude a ( in feet) of a plane t minutes after lift off is given by a=3400t+600 How many minutes after liftoff is the plane at an attitude of 21,000 feet?

I need help understanding this ASAP PLZ!!!

  6 minutes

Step-by-step explanation:

'a' in the formula represents altitude in feet. You are told the altitude is 21000 feet, so put that into the formula:

   21000 = 3400t +600

You can solve this for t:

  20400 = 3400t . . . . . subtract 600 from both sides

  6 = t . . . . . . . . . . . . . . . divide both sides by 3400

The problem statement tells you that t represents minutes after lift off, so this solution means the altitude is 21000 feet 6 minutes after lift off.

The question is asking for the number of minutes after lift off that the plane reaches an altitude of 21000 feet, so this answers the question directly:

  The plane is at an altitude of 21000 feet 6 minutes after lift off.

60

step-by-step explanation:

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.