Question

20. The first four terms of an AP, whose first term is -2 and the common difference is -2 are
[NCERT Exemp
(1) - 2, 0, 2, 4 (6) 2, 4, 8, 16 (c) 2, 4, -6, -8 (d) 2, 4, 8, – 16​

Answer 1

First term(a) = -2

common difference (d) = -2

1st term=-2

2nd term=a+d=-2+(-2)=-4

3rd term=a+2d=-2-4=-6

4rth term =a+3d=-2-6=-8

Answer 2

Given :

• First term (a) = -2

• Common Difference (d) = -2

______________________

To Find :

• Four terms of AP

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Solution :

⇒a = -2

____________

⇒a2 = a + d

⇒a2 = -2 - 2

⇒a2 = -4

____________

⇒a3 = a + 2d

⇒a3 = -2 + 2(-2)

⇒a3 = -2 - 4

⇒a3 = -6

____________

⇒a4 = a + 3d

⇒a4 = -2 + 3(-2)

⇒a4 = -2 -6

⇒a4 = -8

So, AP is -2,-4,-6,-8,..........