Question

5. The sum of the first n terms of an AP is given by Sn = (3n² - 4n). Find its
(i) nth term, (ii) first term and (iii) common difference.​

Answer 1

Answer:

Step-by-step explanation:

Sn=3n²-4n

S₁ =3*1-4*1=3-4 = -1

S2=3(2)²-4*2=12-8=4

S2=T1+T2=4

S1=T1=-1

T2 = 4-(-1) = 4+1 = 5

d=T2-T1=5-(-1)=6

Thu sFirst term S1=a=-1

Common difference d=6

nth tern

Tn= a+(n-1)*6

Tn=-1+6n-6

Tn=6n-7