(1) The 6th term of a G.P is -7 over 32. find its common ratio if its first term is 28.

Answer 1

term n = a r^(n-1)
term 6 = a r^5 = -7/32 and a = 28

-7 / 32 = 28 r^5 = -7/2^5
r^5 =(-7/28)(1/32) = (-1/4)(1/2)^5
r= (1/2)(-1/4)^0.2
I get -.38

Answer 2

??? 7/32 = 0.21875
28 * .38^5 = 0.22185
what went wrong?
r^5 = (-7/28)(1/32) = -(1/4)(1/2)^5 = -1/2^7
r = -1/2^1.4 = -0.37893
check: 28*0.37893^5 = 0.21875