Sigma Notation Part 3

Now I want to expand a little bit on this sigma notation with these parentheses. I told you before, you always do whatever is in the parentheses first. But we can have all kinds of fun stuff in those parentheses. So I want to briefly remind us the order of operations. Whenever we’re doing math, we always do things in a certain order. We’re going to do parentheses first, which we’re doing. Within those parentheses, we need to do other parentheses if present. Then we would do exponents, then multiplication and division, and then addition and subtraction. So how might I do the example on the screen here, 2x minus 1? Remember, x is a set of numbers.

So this is an instruction to multiply every score times 2. And that’s multiplication, so we’ll do that first. Then subtract 1 from that. And then we add it up. So let’s go ahead and see how that might look. This is going to say take every score, 2x minus 1. So we’re going to multiply 2 times 30. And then we’re going to subtract that 1. Then we’re going to have 2 times 21. And then we’re going to subtract that 1, and so on and so forth. So that’s going to give me 60 minus 1, 42 minus 1, and so on and so forth, which will give me a total score of 306.

So we can have all kinds of fun stuff within those parentheses. As long as we follow that order of operations, we can always follow our recipe and get the right final result.