Need help -- math B

[Ixnay]

http://www.nysedregents.org/testing/mathre/b106.pdf

I have a question about the very first question.
What is that big E symbol? I never learned about that in class and all the practice tests we've been using have a question exactly like that.
What is it and how do you solve it??

 

[galactus]

That's not a 'Big E'. It's the Greek letter Sigma(capital).

It denotes summation, to add up a bunch of terms. For instance, if you wanted to add up the numbers from 1 to 100 you would write:

\(\displaystyle \L\\\sum_{k=1}^{100}k\)


For the first problem, you have \(\displaystyle \L\\\sum_{n=1}^{5}(-2n+100)\)

That means add them up using 1 through 5.

\(\displaystyle \L\\(-2(1)+100)+(-2(2)+100)+(-2(3)+100)+(-2(4)+100)+(-2(5)+100)=470\)