Question

in an ap the 4th term and 8th term are 13 and 36 respectively then the common difference is...​

Answer 1

Answer:

4th term=3a+r.....(I)

13=3a+r...

8th term=7a+r......(II)

36=7a+r

now solve eq (I) and (II) by substitution method

by eq (I)

r=13-3a

put value of r in eq (II)

36=7a+(13-3a)

36=7a+13-3a

36-13=4a

23=4a

a=(23/4)

now put value of a in eq (II)

r=13-3(23/4)

r=13-(69/4)

r=(52-69)/4

r=-(17/4)

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