Use the change of base formula to approximate the solution to log0.515 = 1 – 2x. Round to the nearest hundredth.

I'm not sure that the change of base formula would do much good here, since we're already using base 10....here's my approach...

log0.515 = 1 – 2x     and we can write

log0.515  = log 10 - 2x    rearrange

2x = log 10  - log0.515

2x = log (10/0.515)    divide both sides by 2

x = log(10/0.515)/ 2   ≈ 1.288  ≈  1.29 to the nearest hundredth

Hi Chris

I couldn't work out what was wanted either  

Your answer is a good one though.