Hi i was wondering if i could get help with these questions please.
I've tried to do them multiple times with no success
For Question 15, consider the formulae for arithmetic series (\(T_n=a+(n-1)d\)), and geometric series (\(T_n=ar^{n-1}\)). You have two terms for certain, and so can solve for a and d (or a and r). That will let you find x.
Question 13, graph on the right is easier, by how much does each term increase by the one before it? First term is 5, second term is 8, third term is 11, what's the difference there? That will let you find a. The graph on the left is similar, but perhaps trickier, what number are you multiplying by each time?
Question 10, you have:
Then, use the given term to solve for k, and then use that value to solve for the 21st term
Your final question:
You have there a set of simultaneous, that will let you find your missing values!
Most of these questions are fairly standard applications of the same principle: Using the equations and solving simultaneously. Are those equations something you are familiar with and/or do you need help understanding them at all?