Answer:
2r^2+(6+5)r+15=0
2r^2+6r+5r+15=0
2r(r+3)+5(r+3)=0
(r+3)(2r+5)=0
I got 47 because...
Tn = Tn-1 + 3×2^(n -1)
Using the above formula,
T2 = 2 + 3×2^(1-1) = 2 + 3×2^0 = 2 + 3 = 5
T3 = 5+ 3×2^(2-1) = 5 + 6 = 11
T4 = 11 + 3×2^(3-1) = 11 + 12 = 23
T5 = 23 + 3×2^(4-1) = 23 + 24 = 47
