Question

12. Two A.Ps. have the same common difference. The
first term of one of these is -1 and that of the other
is – 8. Then the difference between their 4th terms
is :​

Answer 1

Answer:

Let , the common difference of 1st A.P = d

the common difference of 2nd A.P = d'

Given:- d = d'

and,. t = -1 /. t' = -8

therefore,

a4 - a'4 = t + 3d - ( t' + 3d')

= -1 + 3d - ( -8 + 3d) ..…...(since, d = d')

= -1 + 3d + 8 - 3d

= -1 + 8

a4 - a'4 = 7

Answer 2

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Let , the common difference of 1st A.P = d

the common difference of 2nd A.P = d'

Given:- d = d'

and,. t = -1 /. t' = -8

therefore,

a4 - a'4 = t + 3d - ( t' + 3d')

= -1 + 3d - ( -8 + 3d) ..…...(since, d = d')

= -1 + 3d + 8 - 3d

= -1 + 8

a4 - a'4 = 7