Question

If the sum of first 4 terms of an AP is 4n-n^2.Find the 1st ,2nd ,3rd , 10th and 11th terms

Answer 1

Answer:

Step-by-step explanation:

Let n=1

Then 4 (1)-(1)^2

=4-1 =3 (ie=a)

Let n=2

Then 4 (2)-(2)^2

8-4 =4

-

a1 +a2=S2

3+a2=4

a2=4-3 =1

a+d=a2

3+d=1

d=1-3

=-2

So, a3=a+2d

=3+2 (-2)

=3-4

=-1

a10=a+9d

=3+9(-2)

=3-7

=-4

lly

a 11 =-17

Hope it will help u :) ;)

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