Question

What is the 41st term of the arithmetic sequence where A Subcript 1 = 15 and A subcript15 = –41

Answer 1

a1 = 15 = a + (n - 1)d

SO, a + (1 -1)d = 15

a = 15

Similarly, a15 = -41 = a + (15 - 1)d

a + 14d = -41

14d = -41 - a

14d = -41 - 15

14d = -56

d = -4

So here we are to find 41st term ie a41, so here n = 41

a41 = a + (41 - 1)d = 15 + 40(-4)

a41 = 15 - 160 = -145 is the 41st term...