Question

if three distinct real numbers a,b,c, are in A.P. Then which of the following are also use in A.P.:
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Answer 1

Let d be the common difference of the A.P.

Given, 4=abc

=(b−d)b(b+d)

=b(b

2

−d

2

)

=b

3

−bd

2

Therefore, b

3

=4+bd

2

.

Since b>0 and d

2

≥0, so b

3

≥4.

⇒b≥4

3

1