Write the result in scientific notation. Multiply

Question

(8•10^3)(7•10^5)
A.5.6•10^16
B.5.6•10^9
C.1.5•10^16
D.1.5•10^9
Is the answer A or B?? because 8•7=56 and you put a decimal between the five and six but if I add the exponents I get Eight and if I multiply I get 15??

Answer 1

8 * 10 ^ 3 * 7 * 10 ^ 5 =

8 * 7 * 10 ^ 3 * 10 ^ 5 =

56 * 10 ^ 8 = 5.6 * 10 * 10 ^ 8 = 5.6 * 10 ^ 9

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Remark:

a ^ n * a ^ m = a ^ ( m + n )

10 ^ 3 * 10 ^ 5 = 10 ^ ( 3 + 5 ) = 10 ^ 8

10 = 10 ^ 1

10 * 10 ^ 8 = 10 ^ 1 * 10 ^ 8 = 10 ^ ( 1 + 8 ) = 10 ^ 9
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Answer 2

I don't understand what your meaning I still don't know what the answer is??

Answer 3

Answer B

Answer 4

Thank you.