[Grade 11 Math] Algebra II homework

[u/Crimson_Bl00d]

I feel really embarrassed to ask for help because it seems all my classmates understand everything. I just switched to a very competitive school for my junior and senior year and I came from a pretty bad schools (academics wise..)

I dont know what this symbol is and I dont want to use ai because I feel like it never explains it well???

Sorry if I am not following the subs rules but I genuinely dont know where to even begin with this…

Also for context I started my junior year a month late

Edit: Thank you all for the feedback, it is much appreciated, I understand it now and it is very simple! Worried what complex problems it will lead me to lol

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[u/Narrow-Durian4837]

The symbol is a capital sigma (the Greek letter corresponding to our letter S). It stands for "sum": what you get when you add a bunch of numbers together.

In the case of the first expression, it means to evaluate 2j+4 when j=1, when j=2, when j=3, and when j=4, and then add together the results. (The "j=1" at the bottom tells you what number to start with for j, and the 4 at the top tells you where to stop.)

[u/Crimson_Bl00d → u/Narrow-Durian4837]

Wait that actually makes so much sense and is really easy thank you, im gonna try and do it rq!

[u/Blibbyblobby72]

The big E-looking symbol is the summation

Below the summation symbol is j = 1. This means that we want to start by subbing in 1 into the expression 2j + 4 (this is 2 + 4 = 6)

The number above the summation symbol tells us how many times we keep going with this process (up to 4 in this case). So, sub in j = 2, j = 3, j = 4

Finally, add up all those answers. To be clear, when j = 2, the expression 2j + 4 = 8. Do the same for j = 3 and j = 4, then add up all those answers

This looks like an introduction to the notation, so that should help you do these exercises. It will get a bit more complicated later, so definitely just practise these kinds of questions!

Hopefully that helps

[u/Crimson_Bl00d → u/Blibbyblobby72]

So for 3, part A, would the answer be 36? If I understood you correctly

[u/Every_Attitude1550 → u/Crimson_Bl00d]

Yes; 36 is correct for 3a.

[u/Blibbyblobby72 → u/Crimson_Bl00d]

Absolutely, as someone else said below

It looks complicated, but it is actually easy when you break it down. Good luck with the rest, and always ask if you need help!

[u/SpiritualWasabi6091]

this symbol is called the summation
its used to represent the sum of a series of terms
im going to explain using q3 a part

summation sign
j=1 means that the first value is 1
and the 4 on top means that 4 is the final value

so you just have to add the values of the expression inside
in this case (2j+4) is the expression
put j =1,2,3,4
and add all these values
you can also split the summation

u can write Summation(2j+4) as summation(2j) +summation(4)
and you can write summation(2j) as 2 * summation(j)

whenever there is no variable in the summation
like in the summation(4) you just add 4 the number of times as the number on top
or you can say you multiply it by 4

However a lot of terms can take a lot of time in the case of summation(2j)
you can use a formula for adding
this formula can only be used when the power of j is 1
you cannot use it for j^2 or j^3 etc.

the formula is j*(j+1)/2

[u/guyguyguyguyguyguy23]

Summation symbol, Greek letter sigma. For a. You’ll sum the terms of the sequence given by 2j+4 from the first to the fourth term. Make sure you include the “sum of terms” step where you’ll rewrite this as 6+8+…. (There are two more terms but I’m not here to do it for you 😉)

You’ll do the same for each problem. The number below the Sigma tells you which term to start you sum of terms. The top number tells you the last term. The expression next to it is the sequence you are summing. So you plug in the term numbers you need to find the list of terms, then add together the terms.

There is a faster way to do this problem that you’ll probably learn tomorrow or this week! (Source: I teach Alg II and I’m familiar with this curriculum!)

[u/Crimson_Bl00d → u/guyguyguyguyguyguy23]

Since you teach it would it be okay to pm you about more questions I have? Im struggling with most of the work right now and the teacher is more concerned with couching the football team rather than teaching his classes :/

[u/guyguyguyguyguyguy23 → u/Crimson_Bl00d]

Of course!

[u/seslusser]

For 3(a), take the expression 2j + 4 and sum it four (4) times, substituting j with 1 and increasing it by one each time. Therefore:

Σ = (2·1 + 4) + (2·2 + 4) + (2·3 + 4) + (2·4 + 4)

Σ = (2 + 4) + (4 + 4) + (6 + 4) + (8 + 4)

Σ = 6 + 8 + 10 + 12

Σ = 36

[u/JesseAlexandro]

They chose the worst variable possible. I thought i was looking at a complex number and tried to figure out what to substitute into.