Question

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

Answer 1

yes this is in AP
20TH TERM IS a+19d
-12+19(7)
121 is the 20th term

Answer 2

Given sequence is -12, -5, 2, 9, 16, 23, 30,.....

• As we can see, consecutive numbers have a difference of 7, therefore it is an arithmetic progression (A.P.).

• Comparing with general form Tn = a + (n - 1) * d, where a is the first term and d is the common difference.

• Therefore, a = -12 and d = 7.

• The 20th term will be, T20 = a + (20 - 1) * d,

                                              T20 = -12 + 19 * 7

                                              T20 = -12 + 133

                                              T20 = 121

The 20th term is 121.