an = a1r^(n-1)
a5 = a1 r^(5-1)
-6 =a1 r^4
a2 = a1 r^(2-1)
-48 = a1 r
divide
-6 =a1 r^4
---------------- yields 1/8 = r^3 take the cube root or each side
-48 = a1 r 1/2 = r
an = a1r^(n-1)
an = a1 (1/2)^ (n-1)
-48 = a1 (1/2) ^1
divide by 1/2
-96 = a1
an = -96 (1/2)^ (n-1)
the sum
Sn = a1[(r^n - 1/(r - 1)]
S18 = -96 [( (1/2) ^17 -1/ (1/2 -1)]
=-96 [ (1/2) ^ 17 -1 /-1/2]
= 192 * [-131071/131072]
approximately -192
Reduce all of the mutiple choices
A. 4/3 . It is greater than 3/4. 4/3 as a decimal is 1.333. 3/4= 0.75
B. 12/12. 12/12=1. 1 is greater than 3/4
C. 9/16. Cannot reduce the fraction.
D. 12/16 divide by 4 for the numerator and denominator. 12/4=3 , 16/4= 4
Answer: D. 12/16
I believe, if I'm not correct but I think the answer would be 8 minutes or less.. Considering the fact that the Harris Family left 12 minutes ahead and the Arlen family is Averaging 55 MPH.. Too the speed that the Arlen's are going make the time for them to catch up to the harris's shorter. The Arlen's are going 15 mph faster sooo.. Yeah.. Tell em if this helps! :D
