# Math Help - solving summation notation questions

1. ## solving summation notation questions

Hey, I am having trouble with the following questions:

1.

2
∑ (ax(subscript i)+by(subscript i))
i=0

2.

5
∑ (j^3 - 4j^2 - 2j + 3)
j=3

2. Two questions:

1. What is your goal here? To evaluate the sums?

2. What have you tried so far?

3. Originally Posted by daniel52947
Hey, I am having trouble with the following questions:

1.

2
∑ (ax(subscript i)+by(subscript i))
i=0
Do you understand what that symbol means? Just replace "i" in "ax(subscript i)+ by(subscrpt i)" by 0, 1, and 2 and add.

2.

5
∑ (j^3 - 4j^2 - 2j + 3)
j=3
Again, replace "j" by 3, 4, and 5 and add.
What is j^3- 4j^2- 2j+ 3 when j= 3? That is, what is 3^3- 4(3^2)- 2(3)+ 3? Do the same four j= 4 and 5 and then add those three numbers.