The question asks to "write the terms of each of the following summations." Below are the terms for each summation:

1. (أ)
   $\sum_{i=1}^{5}(x_i + 3)$
   Expand the summation: $(x_1 + 3), (x_2 + 3), (x_3 + 3), (x_4 + 3), (x_5 + 3)$

2. (ب)
   $\sum_{i=1}^{3}c_i x_i^4$
   Expand the summation: $c_1 x_1^4, c_2 x_2^4, c_3 x_3^4$

3. (ج)
   $\sum_{i=1}^{4}z_i(z_i + 4)$
   Expand the summation: $z_1(z_1 + 4), z_2(z_2 + 4), z_3(z_3 + 4), z_4(z_4 + 4)$

4. (د)
   $\sum_{i=1}^{4}(y_i^2 - 3)$
   Expand the summation: $(y_1^2 - 3), (y_2^2 - 3), (y_3^2 - 3), (y_4^2 - 3)$

5. (هـ)
   $\sum_{i=1}^{6}2x_i y_i$
   Expand the summation: $2x_1y_1, 2x_2y_2, 2x_3y_3, 2x_4y_4, 2x_5y_5, 2x_6y_6$

Let me know if you want further details about summation properties or need additional explanations!

Related Questions:

1. How can we generalize the summation formula for arbitrary $n$?
2. What are the properties of linear summations like $\sum (x_i + a)$?
3. How does changing the limits of summation affect the terms?
4. What happens if one of the terms in a summation is zero?
5. Can you calculate the total sum for each case if specific values are provided?

Tip: When working with summations, always focus on the index $i$ and how it varies to generate the individual terms!