Question

10th term of arithmatic sequence is 65 and 15 terms is 80 is 200 terms of tgis sequence
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Answer 1

Step-by-step explanation:

Let a be the first term and d is the common difference, then

a+9d=65a+14d=80

(a+14d)−(a+9d)=80−65⟹5d=15⟹d=3

a+9d=65⟹a+27=65⟹a=38

an=a+(n−1)d⟹200=38+(n−1)3=35+3n

⟹3n=165⟹n=55

∴200 is the 55th term of the arithmetic