Question

Decide whether following sequence is an ap if so find the 20th term of the progress - 12 ,-5,2,9,16,23,30.........

Answer 1

Answer:

121

Step-by-step explanation:

If this is an AP, difference between any term and previous term must be costant.

So, if - 5 - (-12) = 2 - (-5) = 9 - 2 = 16 - 9 = 23 - 16 = 30 - 23, is true, this is an AP.

We found - 5 - (-12) = 2 - (-5) = 9 - 2 = 16 - 9 = 23 - 16 = 30 - 23 is equal to 7.

So this is an AP.

nth term in AP = a + (n - 1)d, where a is first term and d is common difference.

Here,

First term = - 12 & com. dif = 7

So,

= > 20th term = - 12 + (20 - 1)7

= > - 12 + 19(7)

= > - 12 + 133

= > 121