sec exercises use subtract-and-guess or divide-and-guess to find the closed form solution for the following summation you must first find pattern from which to deduce potential closed form solutionand then prove that the proposed solution is correct / = use the shifting method to solve the summation = use the shifting method to solve the summation = use the shifting method to solve the summation - = consider the following code fragment sum inc for ( = <=ni++for ( = <=ij++sum sum incinc++(adetermine summation that defines the final value for variable sum as function of (bdetermine closed-form solution for your summation chocolate company decides to promote its chocolate bars by including coupon with each bar bar costs dollarand with coupons you get free bar so depending on the value of cyou get more than one bar of chocolate for dollar when considering the value of the coupons how much chocolate is dollar worth (as function of ) write and solve recurrence relation to compute the number of times fibr is called in the fibr function of exercise