X²+8x-84=0
Formúla General ​

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How many zeros does the function f(x)=4x3-x2+1 have

The graph shows the distance y, in inches, a pendulum moves to the right (positive displacement) and to the left (negative displacement), for a given number of seconds x. how many seconds are required for the pendulum to move from its resting position and return? enter your answer in the box.