Question

If Tn =3n-2 then the value of T7 +T8 is​

Answer 1

Answer:

tn = 3n -4 ( given)

Substituting n= 1

T1= 3x1–4

= 3–4 = -1

Substituting n=2

T2= 3x2- 4

= 6–4 = 2

The first two terms of the sequence are -1 & 2

Answer 2

Give n=5 in the general term

T 5=3(5)-7 = 15–7 =8

Another method

Tn = 3n - 7

T 1 = 3(1)-7 = -4

T 2 = 3(2) -7= -1

d= t 2 - t 1 = -1 -(-4)=3

a = -4 d=3

Tn = a + (n-1)d =

T 5 = a + (5–1)d = a +4 d = -4 +4(3)= 8