Exponential Functions

[greatwhiteshark]

I have two questions:

State the domain, range and intercepts, if any of f.

1) If 4^(x) = 7, what does 4^(-2x) equal?



2) If 3^(-x) = 2, what does 3^(2x) equal?

 

[jolly]

You're really good in Math. Personally, I feel you should tutor on this site, too. What do you say?

 

[tkhunny]

State the domain, range and intercepts, if any of f.

One would have to define some 'f' in order for there to be a problem to solve, here.

1) If 4^(x) = 7, what does 4^(-2x) equal?

4^(-2x) = [4^(x)]^(-2) = [7]^(-2) = 1/(7^2) = 1/49

2) If 3^(-x) = 2, what does 3^(2x) equal?

3^(2x) = [3^(-x)]^(-2) = [2]^(-2) = 1/(2^2) = 1/4

What did you get on these?

 

[Guest]

Related: http://www.sosmath.com/CBB/viewtopic.php?p=79329

 

[greatwhiteshark]

ok

ok...Thanks

 

[pav]

hello greatwhiteshark

not saying this will work just curious

4^x=7

log4^x=log7

xlog4=log7

x=log7/log4

4^-2x

= 1/4^2(log7/log4)

this doesnt work can anyone tell me why

 

[Gene]

PAV:
Up to the last line. You were trying for
4^(-2x) but you typed
(4^-2)*x
Ya gotta think PEMDAS
1/4^2(log7/log4)
P:
1/4^2*1.403...
E:
1/16*1.403...
MD:
.0876...
But
(1/4)^(2*log7/log4) = .0204...
works.
Look under MATH LESSONS at ORDER OF OPERATIONS for more. If yoe try to put things into a calculator you MUST obey the rules. GIGO.