18. (a) Let A = ⌈ ⌊ 1 0 2 1 ⌉ ⌋ , B = ⌈ ⌊ 2 3 −1 0 ⌉ ⌋ . Find A2 + AB + B2.   19. (b) Ajay owns 560 shares of a company. The face value of each share is Rs.25. The company declares a dividend of 9%. Calculate:- (i) The dividend that Ajay will get.(Type in the answers separated by commas. Leave no spaces around the commas.)   20. (ii) The rate of interest on his investment, if Ajay had paid Rs. 30 for each share.   21. (c) The surface area of a solid metallic sphere is 616 cm2. lt is melted and recast into smaller spheres of diameter 3.5 cm. How many such spheres can be obtained?