The sum of all the solutions of the equation (8)2x - 16 (8)x + 48 = 0 is :
- 1 + 8(6)
- 1 + 6(8)
- 8(6)
- 8(4)
Answer
(1) 1 + 8(6)
Solution
Put 8x = t > 0: t2 - 16t + 48 = 0 (t - 4)(t - 12) = 0
t = 4, 12; both are positive, so there are two solutions x1, x2
8x1 8x2 = 4 12 8x1 + x2 = 48
x1 + x2 = 8 48 = 8(8 6) = 1 + 8(6)
Answer: (1)