I've tried this one over and over.

May 2010
37
0
If 8^x = 15 and 8^y = 25, then 8^(2x+y) =

A) 55
B) 80
C) 250
D) 5,625

When I just input it into the calculator I get 4.676805239 and when I do 15 x 2 + 25 I get 55 but the answer is 5,625.
 
Jun 2009
806
275
If 8^x = 15 and 8^y = 25, then 8^(2x+y) =

A) 55
B) 80
C) 250
D) 5,625

When I just input it into the calculator I get 4.676805239 and when I do 15 x 2 + 25 I get 55 but the answer is 5,625.
\(\displaystyle 8^{2x} = 15^2 and ; 8^y = 25\)

So \(\displaystyle 8^{(2x+y)} = (15^2)(25) = ....?\)
 
May 2010
37
0
Thank you so much. Me and my sister together couldn't figure that one out. (Rofl)