Question

If d‌=-6 of ap,find a16-a12

Answer 1

Solution :

Let the first term = a ,

d = -6 ,

an = a + (n-1)d

a16 - a12

= ( a + 15d ) - ( a + 11d )

= a + 15d - a - 11d

= 15d - 11d

= 4d

= 4 × (-6)

= -24

••••

Answer 2

In an AP,

let a be the first term

Let d be the common difference

Given d=-6

We know that :

nth term of an ap is a+(n-1)d

So a16 is = a+(16-1)d

=a+15d................(1)

a12 is =a+(12-1)d

=a+11d.................(2)

Subtracting (1) and (2) we get:-

a16-a12 = a+15d-(a+11d)

==) a16-a12=a-a+15d-11d

==) a16-a12=4d

The value of d is -4.

So:

a16-a12=4d

==) =4*-6

==) -24

This gives our required answer: -24

Hope it helps you:-)

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