Set both factors equal to 0 and solve. 

n+1 = 0, n = -1

n+9 = 0, n = -9

n= -1, -9

The question is asking, For what values of n will the equation equal zero. So you can break it apart and set each set of parenthesis equal to zero then solve for n. => n+1=0 , n+9=0 so the values of n that make the equation zero are -1 and -9.