3. The first four terms of a sequence are: T2 = 12+ 22
T3 = 12 + 22 + 32
T4 = 12 + 22 + 32 +42
T1 = 12
The n" term is given by Tn=n(n + 1)(2n + 1).
Work out the value of T23.

The 23rd term is 2806.

Step-by-step explanation:

The other answerer has used the formula but i'm answering from the assumption that T1 to T4 are correct.

Each term is the sum of n terms of an arithmetic series with first term a1 = 12 and common difference d = 10.

Sum of n terms = (n/2)[2a1  + d(n - 1)]

So the sum of 23 terms =

= 23/2 (2*12 + 10 * 22)

= 11.5 * 244

= 2806.

easy its decreasing

step-by-step explanation:

because its top point is at the to of the graph on the left side (atleast from the veiw i see it) now if that top point wast in the lower part of the graph it would be increasing hope this have a nice day