SOLUTION: write as a single logarithm=6log base 5 X + log base 5 Y

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: write as a single logarithm=6log base 5 X + log base 5 Y       Log On


   



Question 392349: write as a single logarithm=6log base 5 X + log base 5 Y
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
6log%285%2C+%28x%29%29+%2B+log%285%2C+%28y%29%29
These are not like terms so we cannot just add them. (If it had been 6log%285%2C+%28x%29%29+%2B+log%285%2C+%28x%29%29 then they would have been like terms and adding them would give us 7log%285%2C+%28x%29%29 (just like 6q + q = 7q!)

But there is another way to combine two logarithms with a "+" between them into one. A property of logarithms, log%28a%2C+%28p%29%29+%2B+log%28a%2C+%28q%29%29+=+log%28a%2C+%28p%2Aq%29%29, allows us to combine two logarithms if all of the following are true:
  • There is a "+" between them.
  • The bases of the two logarithms are the same
  • The coefficients of the logarithms are 1's.

Your expression meets the first two requirements. But the first logarithm has a coefficient of 6. If we could eliminate that 6 then we would be in business. Fortunately there is another property of logarithms, q%2Alog%28a%2C+%28p%29%29+=+log%28a%2C+%28p%5Eq%29%29, which allows us to "move" a coefficient into the argument of the logarithm as an exponent. Using this property on the first term we get:
log%285%2C+%28x%5E6%29%29+%2B+log%285%2C+%28y%29%29
Now we can use the first property to combine them into one:
log%285%2C+%28x%5E6%2Ay%29%29