Answer:
After 1.87 seconds the skateboarder is 8 ft from the bottom of the hill.
Step-by-step explanation:
The quadratic function d = –2*x² + 15 models a skateboarder’s distance, in feet, from the bottom of a hill x seconds after the skateboarder starts moving down the hill.
You want to know after how many seconds the skater is 8 feet from the bottom of the hill. That is, with the distance being 8 feet, you want to calculate the time t. Replacing in the expression d by the value of 8 feet:
8=–2*x² + 15
Solving:
8-15 = -2*x²
-7= -2*x²
(-7)÷(-2)= x²
3.5= x²
√3.5=x
1.87= x
After 1.87 seconds the skateboarder is 8 ft from the bottom of the hill.
