Let's go through the problems one by one from the image you've uploaded:

Soal 1:

You are asked to compute the sum of the following series: $\sum_{n=1}^{5} (n^2 + 3n)$ We can break this sum down by computing each term individually and summing them up.

Soal 2:

You need to compute this sum: $\sum_{i=2}^{4} (5i - 3)$ Again, you will evaluate each term from $i = 2$ to $i = 4$ and sum them.

Soal 3:

Given the values $x_1 = 4$, $x_2 = 2$, $x_3 = 1$, and $x_4 = -1$, compute: $\sum_{i=1}^{4} \left( 5x_i + \frac{4}{x_i} \right)$ Substitute each $x_i$ into the expression and compute the sum.

Soal 4:

Given the values $x_1 = 3$, $x_2 = 4$, $x_3 = 1$, $y_1 = 4$, $y_2 = 2$, and $y_3 = -1$, compute: $\sum_{i=1}^{3} \left( x_i^2 + 2x_i \right) \left( 3y_i - 1 \right)^2$ Substitute the provided $x_i$ and $y_i$ values into the expression and compute the result.

I'll calculate these step-by-step. Would you like me to proceed with detailed calculations for each question now?

Here are 5 follow-up questions you might think about:

1. What mathematical rules can we use to simplify sums involving polynomials like in Soal 1?
2. What happens if the limits of the summation in Soal 2 change?
3. How do the values of $x_i$ influence the results in Soal 3?
4. Could there be a general formula for summations like the one in Soal 4?
5. How do changes in the variables $y_i$ affect the final sum in Soal 4?

Tip: When dealing with summations, break them down into individual terms before trying to simplify or calculate.