169 because 13 x 13 = 168
2(3w-2+w)
=2(4w-2)
=8w-4
the formula for solving perimeters is 2(WL). so L=3w-2, because the question said the length is 2 units shorter than 3 times the width, and the width is w. so the final equation is <span>2(3w-2+w), and then you just have to simplify that </span>
Answer:
an = (1 + 2·(n - 1))/2^(n - 1) = 2^(1 - n)·(2·n - 1)
sn = 6 - 2·0.5^n·(2·n + 3)