Find the first, fourth, and eighth term of the sequence a(n)=-3x2 ^n-1

 A(n) = 5.3^(n-1)
first term A(1) = 5.3^(1-1)= 5.3^0 = 5.1 = 5
fourth term A(4) = 5.3^(4-1) = 5.3^3 = 5x27 = 135
8th term A(8) = 5.3^(8-1) = 5.3^7 = 5.3^3.3^3.3 = 5x27x27x3= 15x729 = 10935

hope this helps! ;)