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?

+25 = x

step-by-step explanation:

here x is the hypotenuse of a right triangle whose legs are 7 and 24.   by the pythagorean theorem, 7² + 24² must equal x²:

x² = 49 + 576 = 625.   thus, x = +√625 = +25 = x