Dodo1 Group Title Solve for x. 7^x=e^(x+5) one year ago one year ago

1. ZeHanz

If you take the ln on both sides, you can use the rule: $\ln a^b = b \cdot \ln a$so:$\ln 7^x=\ln e^{x+5}$By the rule, this is equal to$x \cdot \ln7 = (x+5) \ln e$ Of course, you know that ln e = 1, so you can solve for x now...

2. Dodo1

as the matter of fact, I was able to come up with that but im confused when it comes x. so, the answer should be x=5/In(7)?

3. ZeHanz

xln7=x+5, so xln7 - x = 5. Factor out x: x(ln7 - 1)=5. Divide by ln7 -1:$x=\frac{ 5 }{ \ln7 -1 }$

4. Dodo1

wow, that makes sence! thank you so much! :)

5. Dodo1

May I ask another question? im stuck with this math question. 5=55(1.3)^x. for x using logs to slove the equation.