Write the series using summation notation. 9 + 29 + 129 + …

Step-by-step explanation:

We can see that this adds by 20, then 100, and so on. Furthermore, it starts at 9, so we can write this as

∑9+20n

The 9 is because we start with 9, and we have a multiplier of 20, so we put the 20 in there as so. On the bottom of the sum notation, we should have n=1 (as when we plug that in, it's our first number) and at the top you can put a variable k as we don't know the maximum. I don't think I can put numbers at the bottom and top of the sum using the tools I have, so that's why I wrote it out

y-y1=4(x-x1)

step-by-step explanation:

this is point-slope form since you only have 4 as the slope it goes in place of m

hope this : )

(3x-8) or (3x+8)

step-by-step explanation: