• Support PF! Buy your school textbooks, materials and every day products Here!

Equation query

  • Thread starter brenfox
  • Start date
  • #1
71
1

Homework Statement


(3.4)^2x+3 = 8.5. Solve for x

Homework Equations




The Attempt at a Solution


3.4^2x = 8.5/3.4^3 ( divide the equation by 3.4^3. This bit i am not sure about)

2xlog3.4 = log (8.5/3.4^3

x = log (8.5)- 3log(3.4) / 2 log (3.4)

=0.929-1.594/1.063
x = -0.626

This seems to work out when i plug it in to the original equation.
Is there an insert equation icon on the template. Can`t find it!
 

Answers and Replies

  • #2
11,479
5,005
I think you meant to say:

(3.4)^(2x+3) = 8.5. Solve for x.

Right? If not you need to edit your post to fix it.

What do you mean by "an insert equation icon"?
 
  • #3
71
1
Looked at the question again and I have wrote it correctly. 3.4 is in parentheses. Not sure why this is so.

An equation icon makes my equations look neater if you know what I mean!
 
  • #4
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
32,710
5,029
Looked at the question again and I have wrote it correctly.
Are you saying that the original looks exactly like that, using the caret symbol instead of a superscript? Seems unlikely, so what you have posted is probably a rendition. But what you posted is equivalent to 3.42x+3. If you meant 3.42x+3 then you can write it as 3.4^(2x+3). And I feel it is a little simpler to take logs first then solve 2x+3 = log(8.5)/log(3.4).
 
  • #5
71
1
Apologies jedishrfu, I have wrote it down wrong. Thanks haruspex, I should have used parentheses after the caret symbol. You live and learn!!
 

Related Threads on Equation query

  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
5
Views
3K
  • Last Post
Replies
2
Views
2K
Top