Math Question and Answers


Question and Answers Forum

All Questions Topic List
None Questions
Previous in All Question Next in All Question
Previous in None Next in None
Question Number 21504 by mondodotto@gmail.com last updated on 25/Sep/17

	Answered by $@ty@m last updated on 26/Sep/17
	$ATQ S_n =(−1)+1+3+5+......+(2n−3) (i) S_(50) =((50)/2){(−1)+(2×50−3)} =25(−1+97) =25×96 =2400 (ii) S_n =624 (n/2){2a+(n−1)d}=624 (n/2){−2+(n−1)×2}=624 n(−1+n−1)=624 n(n−2)=624 n^2 −2n−624=0 n=((2±(√(4+2496)))/2) n=((2±50)/2) n=26,−24 n=26 {∵n∈N}$
	$A T Q$ $S_{n} = (- 1) + 1 + 3 + 5 + . . . . . . + (2 n - 3)$ $(i) S_{50} = \frac{50}{2} {(- 1) + (2 \times 50 - 3)}$ $= 25 (- 1 + 97)$ $= 25 \times 96$ $= 2400$ $(i i) S_{n} = 624$ $\frac{n}{2} {2 a + (n - 1) d} = 624$ $\frac{n}{2} {- 2 + (n - 1) \times 2} = 624$ $n (- 1 + n - 1) = 624$ $n (n - 2) = 624$ $n^{2} - 2 n - 624 = 0$ $n = \frac{2 \pm \sqrt{4 + 2496}}{2}$ $n = \frac{2 \pm 50}{2}$ $n = 26, - 24$ $n = 26 {∵ n \in N}$
Terms of Service
Privacy Policy
Contact: info@tinkutara.com

Question and Answers Forum