Q10. How many terms of AP 9,17,25.... must be taken to give a sum of 636
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Answered by
1
Answer:
n=12
Step-by-step explanation:
a=9;d=8:S=636
n/2[2a+(n-1)d]
n/2[2(9)+(n-1)8]
n/2[18+8n-8]
636=n/2=[8n+10]
4n²+5n-636=0
4n²+(53-48)n-636=0
4n²+53n-48n-636=0
4n(n-12)+53(n-12)=0
(n-12) (4n+53)=0
*By Zero Product*
n-12=0
n=12
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Answer:
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