Which of the following are APs? If they form an AP, find the common difference $d$ and write three more terms.
$-1.2, -3.2, -5.2, -7.2, ……$

Given:

Given sequence is $-1.2, -3.2, -5.2, -7.2, ……$

To do:

We have to check whether the given sequence is an AP. If it is an AP we have to find the common difference $d$ and write three more terms.

Solution:

In the given sequence,

$a_1=-1.2, a_2=-3.2, a_3=-5.2$

$a_2-a_1=-3.2-(-1.2)=-3.2+1.2=-2$

$a_3-a_2=-5.2-(-3.2)=-5.2+3.2=-2$

$a_2 - a_1 = a_3 - a_2$

$d=a_2 - a_1=-2$

$a_5=a_4+d=-7.2+(-2)=-7.2-2=-9.2$

$a_6=a_5+d=-9.2+(-2)=-9.2-2=-11.2$

$a_7=a_6+d=-11.2+(-2)=-11.2-2=-13.2$