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ℎ ℎ (−1)7=10 __________ |
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Answer»
Here,given a=1 d=4−1=3 and,s
=287 Now, s n
= 2 n
(2A+(n−1)d) ⇒287= 2 n
(2×1+(n−1)3) ⇒287= 2 n
(2+3n−3) ⇒574=n(3n−1) ⇒574=3n 2 −n ⇒3n 2 −n−574=0 onsolvingthequadraticequatonusingformula n= 2a −b± b 2 −4ac
Wegetn=14& 3 −41
[doesnotexist] so,n=14 Now, s n
= 2 n
(a+1) ⇒287= 2 14
(1+x) ⇒574=14(1+x) ⇒(1+x)= 14 574
⇒1+x=41 ⇒x=41−1 ∴x=40 x=40isthesolution.
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