# CAT Quantitative Aptitude Questions | CAT Algebra - Polynomials questions

###### CAT Questions | Algebra | Polynomials - Sum of a Series
CAT Questions

The question is about Sum of a Series. The same series is given in two forms and we need to find out the sum of the series. Polynomials is a simple topic which involves a lot of basic ideas. Make sure that you a get of hold of them by solving these questions. A range of CAT questions can be asked based on this simple concept. -->

Question 18: What is the sum of $$frac{7}{1}\\$ + $\frac{26}{2}\\$ + $\frac{63}{3}\\$ + $\frac{124}{4}\\$ + $\frac{215}{5}\\$ .... 19 terms or 7 + 13 + 21 + 31 + 43 + 57 + 73... 19 terms? 1. 3100 2. 3025 3. 3044 4. 3097 ## 2IIM : Best Online CAT Coaching #### 2IIM's Online CAT CoachingGet CAT Last Mile Prep Course for 799 /-CAT Online Coaching ### Video Explanation ## Best CAT Coaching in Chennai #### CAT Coaching in Chennai - CAT 2020Starts Sat, November 2nd, 2019 ### Explanatory Answer ##### Method of solving this CAT Question from CAT Algebra - Polynomials: How you would go about simplifying the series? $\frac{$2^3−1$}{(2−1)}$ + $\frac{$3^3−1$}{(3−1)}$ + $\frac{$4^3−1$}{(4−1)}$ + $\frac{$5^3−1$}{(5−1)}$ +$\frac{$6^3−1$}{(6−1)}$ … $\frac{$a^3−1$}{(a−1)}$ = a2 + a + 1 So, the above expression becomes$22 + 2 + 1) + (32 + 3 + 1) + (42 + 4 + 1) + ………. + (202 + 20 + 1)
Σn2 + Σn + Σ1 from 2 to 20
$$frac{$n(n+1$(2n+1))}{6}$ + $\frac{$n(n+1$}{2}$ + n-3$for n = 20)
n * ($$frac{$n(n+1$(2n+1))}{6}$ + $\frac{$n+1$}{2}$ + 1) - 3$for n = 20)
n * ($$frac{$2n^2+6n+10$}{6}$) - 3 n *$$$frac{$20(400+60+5$)}{3}$) - 3 = 3100 - 3 = 3097 The question is "What is the sum of $\frac{7}{1}\\$ + $\frac{26}{2}\\$ + $\frac{63}{3}\\$ + $\frac{124}{4}\\$ + $\frac{215}{5}\\$.... 19 terms or 7 + 13 + 21 + 31 + 43 + 57 + 73... 19 terms?" ##### Hence the answer is "3097" Choice D is the correct answer. ###### 2IIM's Online CAT CoachingGet CAT Last Mile Prep Course for 799 /- Signup Now! ###### Already have an Account? ###### CAT Coaching in ChennaiCAT 2020Enroll at 44,000/- Next Weekend Batch Starts Sat, Nov 2nd, 2019 ###### Best CAT Coaching in ChennaiRegister Online, get Rs 4000/- off Attend a Demo Class ##### Where is 2IIM located? 2IIM Online CAT Coaching A Fermat Education Initiative, 58/16, Indira Gandhi Street, Kaveri Rangan Nagar, Saligramam, Chennai 600 093 ##### How to reach 2IIM? Phone:$91) 44 4505 8484
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