Question

In an A.P, the difference between the 8th and 4th term is 20 and 8th term is 1.5 times the first term. Find
a) common difference
b) first term

Answer 1

Step-by-step explanation:

if a is the first term and d is the common difference then,

4th term =a+3d

8th term=a+7d

a/q

a+7d-(a+3d)=20

=>a+7d-a-3d=20

=>4d=20

=>d=20/4

=>d =5

again,

a+7d = 1.5a

=>0.5a=7d

=>a=(7×5)/0.5

=>a=35/0.5

=>a= 350/5

=>a=70

so, first term is 70 and common difference is 5.

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