Question

Which term of the ap 3,8,,10,12....will be 55 more than its 20th term?

Answer 1

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Here, we will use the formula to find the nth term i.e. aₙ=a+(n-1)d, where a is the first term ,aₙ is the nth term , n is the number of terms and d is the common difference.

Coming to the question.

a=3, d=5, aₙ=55 more than the 20th term i.e.

aₙ=55+{3+(20-1)5= 55+{3+95}=55+98= 153

according to formula,

aₙ= a+(n-1)d

153=3+(n-1)5

150=n×5-5

155=5n

therefore,n=31.(solved).