write the expression an-ak for the ap: a,a+d,a+2d,....... hence find the common difference of the ap for which 20th term is 10 more than the 18 th term.
pl.give full solution
Assum that the first term of the A.P. is a and the common difference is d,
Then the nth term is given by the formula
nth term= a+(n-1)d
Acording to the question,
required expression =[a+(n-1)d]-[a+(k-1)d]=(n-k)d
when the 20th term is 10 more than the 18 th term,
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