4. Determine the number of integer solutions of x + x2 + 13, + x, - 32, where a) xi 20, 1sis4 b) x,,X2 2 2,x3, x4 2 1 Let A be a subset of { 1,2,3, elements in B. Prove that there are distinct subsets C, D of A such that lC|-|D|-5 and sc-sD. 5. ,25) where l Al = 9. For any subset B of A let SB denote the sum of the