Posted by **anonymous** on Tuesday, June 8, 2010 at 6:22pm.

I got this question, and found what I believe to be the solution, but want it confirmed.

I started with:

log[base5](2x+1) + log[base5](x-1) = 1

And used the product law:

log[base5]((2x+1)(x-1)) = 1

log[base5](2x^2-x-1) = 1

Then I changed to exponential form:

5^1 = 2x^2-x-1

5 = 2x^2-x-1

5-5 = 2x^2-x-1-5

0 = 2x^2-x-6

Then, to find x I used the quadratic formula, ending up with:

x = (1 [+ or -] 5) / 4

The second value of x, -1, was inadmissable, so my final value for x was 3/2.

Is that correct?

- Maths -
**Reiny**, Tuesday, June 8, 2010 at 8:10pm
Your equation up to

2x^2-x-6 = 0 is correct, but I factored it to get

(2x+3)(x-2)

so x = 2 or x = -3/2 which is inadmissable

check:

if x=2

LS = log_{5} 5 + log_{5}1

= 1+0 = 1 = RS

so x = 2

- Maths -
**anonymous**, Tuesday, June 8, 2010 at 8:29pm
Thank you :) One question, however. Where did you get LS = log[base5]5 + log[base5]1?

At the beginning, LS = log[base5](2x+2) + log[base5](x-1)

Sorry, it just confused me, it would help if you'd explain that.

- please come back... i still have questions -
**anonymous**, Tuesday, June 8, 2010 at 8:43pm
Please? ^

## Answer This Question

## Related Questions

- Pre-Calc Help please - Solve for x: log base5 (4x) + log base5 (x) = log base5 (...
- Math: Algebra2 Logarithms - Can someone help me find the value of B in this ...
- Calculus - Find A so that 5log(base5)16807 − 3log(base5)7 = log (base5)A I...
- mathematics - Need help with these: Write the expression as a logarithm of a ...
- Math - log(base5)x+log(base25)x+log(base125)x=33 solve for x
- Precalculus - Solve each exponential equation. Give answers as decimals accurate...
- Algebra 2 - What is X? log(base 5)x^10-log(base5)x^6=21
- math - Logarithm!!! Select all of the following that are true statements: (a) ...
- maths - find the value of 81 (1/ log base5 rash to 3 +27 log base 9 rash to 36 +...
- math - find the inverse of f(x)=-5+log(base5)(y-5)

More Related Questions