The two questions are here, they're probably easy but I'm having a brain freeze lol
The 4(c) sequence is 5, 7, 9, 11....
The 4(d) sequence is 5, -10, 20, -40.....
is an ARITHMETIC SEQUENCE.
To sum all the terms of the sequence, the sum is
which is the average value multiplied by the number of terms.
The next term is the previous one multiplied by
This is a GEOMETRIC SEQUENCE.
The sum of these terms is
where "a"=1st term, "r"=common ratio.