Design and Analysis of Algorithms

algorithms & data structures discussion question and need an explanation and answer to help me learn.

please check the instruction and answer the questions in your own words.
Requirements:
Question One
Which algorithm design technique and variation does the below figure represent? What it is the magnitude used here in this figure to change the size of the original problem when applying the techniqueis? Write the formula governing the relationship between the size of the original problem and the changed size of the problem showing the variation of the formula when n>0 or when n=0?
Question Two
Describe the Divide-and-conquer algorithm design technique using graph and showing the details of Divide-and-conquer plan.
Apply the Merge sort algorithm on the following array using graph and showing all the steps to be used.
Question Three

Solve the following system of equations by Gaussian elimination method.
2×1 − x2 + x3 = 1
4×1 + x2 − x3 = 5
x1 + x2 + x3 = 0
Question Four
Construct a heap for the Array = {1, 3, 5, 4, 6, 13, 10, 9, 8, 15, 17}.