Find the greatest common factor of 28x^2 16x

Compare these two waves: the blue and orange waves have the same pitch, but the blue wave is louder. the blue and orange waves have the same volume, but the blue wave has a higher pitch. the orange wave has a higher pitch, but the blue wave is louder. the blue wave has a higher pitch, but the orange wave is louder.

The parabola opens: y=√x-4 (principal square root) up down right left

What is the lcm of 16 and 40 ? 24 and 40 ?