Question

The sum of the first 7 terms of an AP is 63 and the sum of the next 7 terms is 161 find the 28 term

Answer 1

Answer:

60

Step-by-step explanation:

Refer the attached

Please ignore the trigno part

Hope it is help full to u

Answer 2

Answer:

57 plz mark as brainliest

Step-by-step explanation:

S7=63

S14-7=161

S14-63=161

S14=161+63

S14=224

now,S7=63

7/2[2a+(n-1)d]=63

2a+(2n-1)d=63/7×2

2a+(n-1)d=18

2a+(7-1)d=18

2a+6d=18---------equation 1

now,S14=224

14/2[2a+13d]=224

2a+13d=224/14×2

2a+13d=32--------equation 2

solving equations 1 and 2 by eliminating

2a+6d=18

2a+13d=32

-7d=-14

d=-2

put d=2 in equation 1

we will get a =3

now,a28=a+ (n-1)d

3+27(2)

3+54

57