HELP ME HOW DO I PUT INTO MY CALCULATOR AND SOLVE THIS : What is the solution to the equation 7 ^−3x ≈ 9?

Question

tkhunny · Answer

Have you considered graphing $f(x) = 7^{-3x}-9$?

phi · Answer

another way is to do some preliminary work on paper:
$$ 7^{-3x}= 9 $$
"Take the log (base 10 for example) " of both sides

can you write down what  you get ?

iwanttogotostanford · Answer

@phi I am doing a pre-worksheet for the chapter, our teacher makes us try to figure out how to do them ourselves for a grade before we actually learn the chapter,,,, so I have no idea how to do this

iwanttogotostanford · Answer

@tkhunny ^^^

tkhunny · Answer

"our teacher makes us try to figure out how to do them ourselves "

Well, there you go.  You had better get started.

iwanttogotostanford · Answer

@tkhunny we can use online resources goodness i know what i can and can't do

phi · Answer

"Take the log" of , for example, 3  means write log(3)
if you had an equation
a = b
take the log of both sides means write
log(a)= log(b)

you do that to your equation
and then, on the left side you use this property of logs:
$$ \log\left( a^b\right) = b \log(a) $$
to rewrite the left side.

iwanttogotostanford · Answer

ok, thank you! @phi