Logarithmic Equations (Gr. 12)

Solve log(2x+10) = 2

The answer is x = 45 but for some reason I got a different answer and I don't know what I'm doing wrong :S

This is what I did:

log(2x+10) = 2
10^log(2x+10 = 10^2
2x+10 = 2
x = -4

The 3rd line of your solution is incorrect. It should read

2x+10 = 100
Hence x=45.

You should know that if the base is not shown, it is always 10.

log(base10)(2x+10) = 2

10^2 = 2x + 10

100 = 2x + 10

90 = 2x

x = 45


Your steps look right except when you came to 10^2. 10^2 is 100, so I have no idea where you pulled that 2 from. It should be '2x + 10 = 100' not '2x + 10 = 2'.

log(2x+10) = 2
2x +10 = 10^2
2x +10= 100
2x = 90
x =45