Sequences help

Here are the questions:

Find the first six terms , u1= 1 Un+1=Un +2n+1


I know I am meant to substitue the u=1, but not sure where :s and what the 2n is doing there is confusing.

$u_1 = 1$
$u_{n+1} = u_n +2n + 1$

The first line tells you that $u_1 = 1$. To find $u_2$, substitute $u_1 = 1$ and n=1 into the second line to get
$u_{1+1} = 1 + (2*1) + 1$
$u_2 = 4$
Then you can repeat the process to find $u_3$ bu substituting in n=2, and $u_2=4$ and so on to get up to $u_6$



if you know that $x_{n+1} = 0.2(c-3x_n)$ and $x_1 = 8$, using a similar method to the first question, you can say that:
$x_2 = 0.2(c - (3*8))$
Then equate both expressions for $x_2$ and solve to find c.

Edit: beaten to it ^^

$u_2 = u_{1+1} = u_1 + 2 \times 1 + 1 = 1 + 2 + 1 = 4$

Can you see what I've done?

No your explanation is worthey

For the first part when I repeat the proces, I get:

U3= 2 + (2*2) +1, and that gives me U3=7 when it is 9 in the answers

For second part I open it and get 0.2c-4.8:

Then equating 8=0.2c-4.8

c=12.8/0.2
= 64


Is that right?

I think for the first question, you've done $u_{n+1} = n + 2n + 1$ rather than $u_{n+1} = u_n + 2n + 1$:
$u_3 = u_2 + (2*2) + 1$

Your answer to the second question is wrong because you're equating it to $x_1$ rather than $x_2$.