The sum of the firstnith term of series is given by Sn = n2+ 5 n-6. Find the
general term (tn) and (+20)

Tn = 2n+4

T20 = 44

Step-by-step explanation:

Given Sn = n²+ 5 n-6

Tn = Sn - Sn-1

Sn-1 = (n-1)² + 5(n-1) - 6

Tn = n²+ 5n-6 - ((n-1)² + 5(n-1) - 6))

Tn = n²+ 5n-6-(n²-2n+1+5n-5-6)

Tn = n²+ 5n-6-n²+2n-1-5n+5+6

Tn = 2n-7+11

Tn = 2n+4

Get the general term is 2n+4

To get the 20th term;

T20 = 2(20) + 4

T20 = 40+4

T20 = 44

Hence the 20th term of the sequence is 44

The correct answers to your question is
First, Decreasing Linearly, it can be seen after plotting.

Then the answer is


And since asked only for correct choices I haven't shown the calculations.

Hope it helps you.

:)