5! Is the same as 5x4x3x2x1 and 4! Is the same as 4x3x2x1 because 4! Is in the denominator it cancels the 4x3x2x1 in the numerator and you are left with 5x(3!) witch is the same a 5x3x2x1. The answer=30
Alright remember, if any individual factor on the left side of the equation is equal to 0, the entire expression will be equal to 0.
k+1=0
k-5=0
Set the first factor equal to 0 and solve
k=-1
Set the next factor equal to 0 and solve
k=5
The final solution is all the values that make (k+1)(k-5)=0 true.
k=-1, 5
Hope this helped you out :)
4 because 1/4 is basically dividing by 4