Answer ASAP please, i got stuck with this question and I need to know how to answer it

What signals you that factoring by grouping is the best method to use when factoring a problem?

Evaluate-27 ^4/3/8 a) - 81/16 b) 81/16 c) 16/81

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.