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10 is a product of 2 and 5.
49 is a power of 7.
50 is a product of 2 and 25.
56 is a product of 7 and 8.
a+b
2c
a+2b
3a+c
We are given the values of log_x2, log_x5, and log_x7. To write log_x10 in terms of the given logarithms, let's first recall three useful Properties of Logarithms.
| Properties of Logarithms | |||
|---|---|---|---|
| Name | Product Property | Quotient Property | Power Property |
| Condition | a>0, b>0, and x ≠1 | a>0, b>0, and x ≠1 | m>0, b>0, and b ≠1 |
| Property | log_x ab = log_x a + log_x b | log_x ab=log_x a - log_x b | log_b m^p = p log_b m |
According to the Product Property, the logarithm of a product is the same as the sum of the logarithms of its factors. Note that
10 is a product of 2 and 5.
Therefore, log_x10=a+b.
Same as in Part A, we will use the Properties of Logarithms. According to the Power Property, the logarithm of a power is the product of the logarithm and the exponent. Note that 49 is a square of 7.
log_x49 = log_x7^2
Therefore, log_x49=2c.
Once again, to find log_x50 we will use the Properties of Logarithms. Before we do that, we should find factors of 50. Since 50 is even, it is divisible by 2.
log_x50=log_x( 2*25)
By the Product Property, the logarithm of a product is the same as a sum of the logarithms of its factors.
Therefore, log_x50=a+2b.
Finally, let's find log_x56. To do so we should first find factors of 56. Note that 56 is divisible by 7.
log_x57=log_x( 7*8)
By the Product Property, we can write the logarithm as a sum of logarithms.
Therefore, log_x56=3a+c.