80 units
Explanation:
Step 1 :
Given,
The function representing the height is y = 4x^2-32x+80
where the x represents the time after they jumped and y represents their height above ground.
We need to find the platform's height.
Step 2 :
Since x represents the time after they jumped, x = 0 when they have not started jumping and the corresponding y will give the height before they start jumping which would be the height of the platform
Step 3:
When x = 0 we have
y = 0-0+80 = 80
So the height of the given platform is 80 units.