# Quick Algebra Ques

Discussion in 'Community Discussion' started by rdf8585, Jul 13, 2006.

1. ### rdf8585 macrumors regular

Joined:
Feb 15, 2006
#1
I need to find the value of the exponential function y=2.50(3.50)^1.4x when x is = 2

Does that mean y=2.50(3.50)^1.42

or

y=2.50(3.50)^1.4(2)

???

2. ### EricNau Moderator emeritus

Joined:
Apr 27, 2005
Location:
San Francisco, CA
3. ### pknz macrumors 68020

Joined:
Mar 22, 2005
Location:
NZ
#3
<_<

>_>

I did not read this then run away. Ummm my battery died?

Edit: Actually thats not hard at all, I believe EricNau is correct

### Staff Member

Joined:
Sep 19, 2002
Location:
Los Angeles
#4
Google doesn't interpret it right unless you parenthesize properly:

5. ### savar macrumors 68000

Joined:
Jun 6, 2003
Location:
District of Columbia
#5
Huh?

2.50(3.50)^1.4(2)

Order of operations is ^ before *

6. ### rdf8585 thread starter macrumors regular

Joined:
Feb 15, 2006
#6
3. Solve this exponential equation for x: e^5x= 1 over e^2x+7

4. Solve this exponential equation for x: 2^4x-7=32

3...... -1
4....... no idea........

### Staff Member

Joined:
Sep 19, 2002
Location:
Los Angeles
#7
I disagree. Look at the original problem: y=2.50(3.50)^1.4x. I don't think that's intended to be 2.50 * (3.50 ^ 1.4) * x. I think the product 1.4x is to be treated as the exponent, i.e., 2.50 * ( 3.50 ^ ( 1.4 * x ) ). But if you change x to a constant value, 2.50(3.50)^1.4(2), Google doesn't handle it way rdf8585's problem requires.

In other words, I would interpret 2 ^ 3 * 4 as (2^3)*4, as Google does, but I would interpret 2 ^ 3x as 2 ^ (3 * x) because with the juxtaposition implying implicit multiplication. So my point is that you have to add more parens to get the right answer from Google.

8. ### Bobdude161 macrumors 65816

Joined:
Mar 12, 2006
Location:
N'Albany, Indiana
#8
I wouldn't be using Google all that much to calculate my Algebra problems. I used to have Maple and that piece of software had so many options to solving any equation you could think of. I would know, I had to take a class that taught how to use the software, barely passed it.

9. ### pknz macrumors 68020

Joined:
Mar 22, 2005
Location:
NZ
#9
Asking a mathematical question on MR is guaranteed to start a quarrel.

Its odd that Maths is so 'opinionated.'

### Staff Member

Joined:
Sep 19, 2002
Location:
Los Angeles
#10
It's my fault we're talking about math. I meant the discussion to be about teaching errors, but since my examples were about math, and I can't resist talking about math, I'll have to take the blame.

Joined:
Aug 20, 2005
Location:
London, UK
#11
3) x = -1

4) x = 3