- #1

- 6

- 0

what i have done is as follows

3.4^2x = 11.56

3.4^2x+3 = 14.56

8.5 - 14.56 = x

x=-6.06 <<<<is this the correct way of solving and correct answer??

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- Thread starter steveandy2002
- Start date

- #1

- 6

- 0

what i have done is as follows

3.4^2x = 11.56

3.4^2x+3 = 14.56

8.5 - 14.56 = x

x=-6.06 <<<<is this the correct way of solving and correct answer??

- #2

- 147

- 2

Hi SteveAndy

Your formula is a bit confusing:

(3.4)^2x+3=8.5

Should the formula look like this:

1. 3.4^{(2x+3)}=8.5

or

2. 3.4^{2x}+3=8.5

1 or 2?

Your formula is a bit confusing:

(3.4)^2x+3=8.5

Should the formula look like this:

1. 3.4

or

2. 3.4

1 or 2?

Last edited:

- #3

- 147

- 2

if it is :

3.4^{(2x+3)}=8.5

take the log of both sides.....

3.4

take the log of both sides.....

- #4

Mark44

Mentor

- 35,292

- 7,149

3.4

Putting aside the uncertainty of what the original equation actually is, how did you go from the first equation to the second? The 11.56 in the second equation happens to be 3.4steveandy2002 said:I need to find x from (3.4)^2x+3=8.5

what i have done is as follows

3.4^2x = 11.56

3.4^2x+3 = 14.56

8.5 - 14.56 = x

x=-6.06

- #5

- 6

- 0

if it is :

3.4^{(2x+3)}=8.5

take the log of both sides.....

so based on useing logs would the folllowing be correct??

3.4^(2x+3)=8.5

2x+3log3.4=log8.5

2x=3-log8.5/log3.4

x= 3-log8.5/log3.4/2

x=1.947942814?

- #6

- 147

- 2

so based on useing logs would the folllowing be correct??

3.4^(2x+3)=8.5

2x+3log3.4=log8.5

2x=3-log8.5/log3.4

x= 3-log8.5/log3.4/2

x=1.947942814?

Should be:

3.4

exponent rule first:

3.4

so....

3.4

so....

3.4

Now log both sides...

ln(3.4

apply log rule:

2xln(3.4) = ln(8.5/3.4

therefore:

x = ln(8.5/3.4

I get approx: -0.63 for x.

and to check:

3.4

3.4

8.4 = 8.5

hmm... too much rounding, but close enough!

- #7

Mark44

Mentor

- 35,292

- 7,149

The equation above is incorrect. It should beso based on useing logs would the folllowing be correct??

3.4^(2x+3)=8.5

2x+3log3.4=log8.5

(2x + 3)log3.4 = log8.5

This is wrong as well.2x=3-log8.5/log3.4

Starting from (2x + 3)log3.4 = log8.5 there is no way you can get to 2x=3-log8.5/log3.4

x= 3-log8.5/log3.4/2

x=1.947942814?

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