Question

the sum of the first nth term of an AP is given by the formula Sn=3n2+n then 3rd term is​

Answer 1

$\huge{\underline{\red{\fcolorbox{red}{black}{Answer}}}}$

$\large\underline{\bf{⤇given}}$

• sum of n term is 3n²+n
• Find term T3

$\large\underline{\bf{⤇steps}}$

• First find 1st term
• second find d by difference of T2 and T1
• now we have a and d both so we get esily term 3

$\underline{\bf{⤇s1 = T2}}$

• a = 3(1)² + 1
• a = 3 + 1
• a = 4

$\underline{\bf{⤇find \: d}}$

• T1+T2 = S2
• a+a+d = 3n²+n
• 2(4)+d = 3(2)²+2
• 8+d = 12+2
• d = 14-8
• d = 6

$\large\underline{\bf{⤇T3 = ??}}$

• T3 = a+2d
• T3 = 4+2(6)
• T3 = 4+12
• T3 = 16

$\huge{\underline{\red{\fcolorbox{red}{black}{please \: like}}}}$