Solve the problem.
-If a rock falls from a height of 40 meters on Earth, the height H (in meters) after x seconds is approximately $$H ( x ) = 40 - 4.9 x ^ { 2 }$$ When does the rock strike the ground? Round to the nearest hundredth, if necessary.
A) 1.67 sec
B) 8.16 sec
C) 2.86 sec
D) 1.29 sec

Question

Quizplus · Accepted Answer

The rock strikes the ground when the height H is 0. Setting the equation 40 - 4.9x^2 = 0 and solving for x gives x ≈ 2.86 seconds.

Solve the Problem H(x)=40−4.9x2H ( x ) = 40 - 4.9 x ^ { 2 }H(x)=40−4.9x2

Solve the Problem $H ( x ) = 40 - 4.9 x ^ { 2 }$