Question 2837
 For the two similar solids, the scalar  factor 1:2 means their ratio in
 length. Hence, their ratio in volume should be 1^3:2^3 = 1:8.

 Now, we have  (x-2):(x^2-1) = 1:8,
 So, x^2-1 = 8(x-2), or  x^2- 8x + 15 = 0.

 Factoring (x-3)(x-5) = 0, we have x=3 or 5.

 Kenny