Explain how finding the nth element in a pattern is using deduction

Select a graph that have an equation with a < 0

Find the magnitude, correct to two decimal places, made by each of the following with positive direction of the x axis a) y= x the answer is 45° but i don’t know how

Which spreadsheet would be used to compute the first nine terms of the geometric sequence a^n=32•(1/2)n-1