Question

5times ot 5th term is equal to 10 times 10th term find 15th term and find sum of 15thand17th term

Answer 1

We know the formula for finding the nth term i.e. a+(n-1)d.

Now, As per the question,

5{a+(5-1)d} = 10{a+(10-1)d}

5{a+4d} = 10{a+9d}

5a+20d = 10a +90d

-5a = 70d

a= -14d.

a+14d = 0

a+ (15-1)d = 0, which is 15th term.

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