Here's the question you clicked on:
burhan101
Solve for x
\[\huge (5)(8)^{(x+2)} = 5^{7x}\]
\[5 \dot\ 8^{x+2} = 5^{7x} \\ 5 \dot\ 8^x 8^2 = \left(5{^7}\right)^x \\5 \dot\ 8^2 = \frac{\left(5{^7}\right)^x}{8^x} \\5 \dot\ 64 = \left(\frac{5^7}{8}\right)^x \\320 = \left(\frac{5^7}{8}\right)^x \] Take logs of both sides and finish simplifying
|dw:1359086666173:dw|
this is what i'm getting, but it is wrong
wait, we're we sipposed to take the log of both sides?
\[\ln(320) = \ln\left(\left(\frac{5^7}{8}\right)^x\right) \\\ln(320) = x \ln\left(\frac{5^7}{8}\right) \\\frac{\ln(320)}{\ln\left(\frac{5^7}{8}\right)} = x \\\frac{\ln(320)}{\ln5^7 - \ln2^3} = x \\\frac{\ln(320)}{7\ln5 - 3\ln2} = x\]
Uh, ya....logs of both sides. What you do to one side, you do to the other side.
The last two lines, either form, is what you want.
By the way, don't forget that you are isolating x bro. Don't confuse the numerator and the denominator.
yeah i know but im getting a weird answer idk why -.-
You should have gotten what I got above. And if you're approximating, you should get x ≈ 0.628
You did not isolate x properly bro.
Take a look at your second to last step.
ohhh, i figured it. i flipped it
got it ! thanks man :)