Question

in an AP if Sn=4n-n²,then the value of a3 is​

Answer 1

Given :- in an AP if Sn=4n-n²,then the value of a3 is ?

Solution :-

→ Sn = 4n - n²

putting n = 1 we get,

→ S1 = 4*1 - (1)² = 4 - 1 = 3 = a1 = First term .

and,

→ S2 = 4*2 - (2)² = 8 - 4 = 4 = a1 + a2

so,

→ a2 = 4 - 3 = 1

then,

→ common difference = d = a2 - a1 = 1 - 3 = (-2)

therefore,

→ a3 = a + (3 - 1)d

→ a3 = 3 + 2 * (-2)

→ a3 = 3 - 4

→ a3 = (-1) (Ans.)

Learn more :-

evaluate the expression given by 83 - 81 + 87 - 85 +__________ + 395 - 393 + 399 - 397

https://brainly.in/question/14081691

If the nth term of an AP is (2n+5),the sum of first10 terms is

https://brainly.in/question/23676839

Answer 2

Given : Sₙ=4n-n²,

To Find :   the value of a₃

Solution:

a₃   = S₃ - S₂

=> a₃   = 4*3 -3² -   (4*2 -2² )

=> a₃   = 12 -9  -   (8 -4 )

=> a₃   = 3  -   (4 )

=>  a₃   = - 1

Learn More"

a,a+d,a+2d .l and n terms of an AP find ( n-1)

brainly.in/question/7612734

FIRST term if an AP is 4 and the common difference is 3 its 12th term ...

brainly.in/question/7843059

a =3 d=101 Then For A.P Sn - Brainly.in

brainly.in/question/13170418