Question

The sum of first n terms of an ap is given by n square 5n find the 25th term of the ap

Answer 1

did you mean S=n^2+5n__________(1)

S1=1+5*1=6=a. (by eq 1)

S2=4+5*2=14=a+a2

a2=S2-a=14-6=8

a2=a+d

8=6+d

d=2

a25=a+24d=6+24*2=6+48=54

Answer 2

Answer:

a25 = 52

Step-by-step explanation:

n² + 5n

S1 = 1 + 5 = 6 ------- (i)

S2 = (2)² + 5(2) = 4 + 10 = a + a2

=14

S2 = a + a2

14 = 6 + a2

14 - 6 = a2

8 = a2

a2 = a + d

8 = 6 + d

8 - 6 = d

2 = d

an = a + (n-1)d

a25 = 6 + (25-1)2

=6 + 24 × 2

= 6 + 48

a26 = 52

HOPE IT WILL HELP YOU !!