Question

Sequences :/
Dont know how to do the circled parts

Answer 1

\(U_n=T_{n+1}-T_n\)

Answer 2

how? :/

Answer 3

look at the pattern

\(U_1=T_2-T_1\)
\(U_2=T_3-T_2\)
\(U_3=T_4-T_3\)
\(U_4=T_5-T_4\)
.
.
.
\(U_{5075}=T_{5076}-T_{5075}\)
.
.
\(U_{n}=T_{n+1}-T_n\)

Answer 4

@zzr0ck3r but the mark scheme answer says its (n + 1)^2
or n^2+ 2n + 1

Answer 5

This is for the first one you have circled.

Answer 6

yeah

Answer 7

the Un one

Answer 8

Ah we need to plug in the general formula for T_n

so we get


\(U_n=T_{n+1}-T_n=\frac{1}{6}(n+1)(n+2)(2(n+1)+1)-\frac{1}{6}n(n+1)(2n+1)=\\(n+1)^2\)

Answer 9

Understand?