Which rule describes a linear relation?

Brent wants to know what is 5 x 1/2

Enter the number of complex zeros for the polynomial function f(x) = x 4+ 5x² +6

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)