Log3 (4x+1) log3(13x-5)=2
assuming base 3,
log((4x+1)(13x-5)) = 2
(4x+1)(13x-5) = 3^2 = 9
52x^2 - 7x - 5 = 9
Now just solve the quadratic
let Log3 (4x+1) = a and
log3(13x-5) = b , where x > 5/13
then ab = 2 --> b = 2/a
3^a = 4x+1
x = (3^a - 1)/4
3^b = 13x-5
x = (3^b + 5)/13
(3^a - 1)/4 = (3^(2/a) + 5)/13
arggghhh, let's see what Wolfram says, (I changed the a to x, Wolfram did not like the a)
http://www.wolframalpha.com/input/?i=solve+%283%5Ex+-+1%29%2F4+%3D+%283%5E%282%2Fx%29+%2B+5%29%2F13
a = 1.3052
then 3^1.3052 = 4x+1
4x = 3^1.3052 - 1
x = .98766171
looks like I could just as well just plugged the original equation into Wolfram:
http://www.wolframalpha.com/input/?i=solve+Log3+%284x%2B1%29+log3%2813x-5%29%3D2
Where did you get this question?
What level of math is this?
mmmhhh,
I thought logA + logB = log(AB)
I suspect a typo in the original question.
To solve the equation log3(4x+1) * log3(13x-5) = 2, we can use the properties of logarithms.
First, let's rewrite the equation using the properties of logarithms:
log3(4x+1) * log3(13x-5) = log3(3^2)
Using the property loga(x) * loga(y) = loga(x * y), we can simplify further:
log3(4x+1) * log3(13x-5) = log3(9)
Since we have the same base on both sides of the equation (base 3), we can equate the arguments:
(4x+1) * (13x-5) = 9
Let's solve this quadratic equation:
52x^2 - 15x - 20 = 9
Rearranging and simplifying:
52x^2 - 15x - 29 = 0
Now we can use the quadratic formula to find the values of x:
x = (-b ± √(b^2 - 4ac))/(2a)
In this equation, a = 52, b = -15, and c = -29. Plugging these values into the quadratic formula, we can find the solutions for x.