Question

What is the missing value?



A.
−13

B.
−5

C.
5

D.
13

Answer 1

http://static.k12.com/bank_packages/files/media/mathml_d8c79c9c8eecdf3168f484cd4b893f9b730e11df_1.gif

Answer 2

recall...

Answer 3

\[\frac{ 8^a }{ 8^b } = 8^{a - b}\]

Answer 4

can you help me @DanJS and @cwrw238

Answer 5

something + 4 = 9

Answer 6

a = not known
b = -4

a - b = a-(-4) = a+ 4 = 9

a + 4 = 9

Answer 7

so that letter is it is it C

Answer 8

yep

Answer 9

thx

Answer 10

is it C @Michele_Laino

Answer 11

\[\frac{ 8^a }{ 8^{-4} } = 8^{a -(-4)} = 8^{a+4} = 8^9\]

Answer 12

since it is the same base, you can equate the powers

a + 4 = 9

Answer 13

okay thx

Answer 14

just remember when you move a base to a power to the opposite side of a fraction... you switch the sign on the power, + to - or - to +

Answer 15

@brucebaner please follow the good reasoning of @DanJS , solve the equation a+4=9
for a

Answer 16

thx so much @Michele_Laino and @DanJS

Answer 17

your welcome, anytime

Answer 18

thanks! @brucebaner