Stuck On Order of Operations and Exponents.

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MurraySchwartz

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Oct 16, 2013
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I am having trouble understanding how to apply exponents to the following problem:


I = 1260/9.81*1.19[(2/1.19-1)(2/1.19+1)^(1.19+1/1.19-1)]^1/2

The answer I am getting is a tremendously huge number which I am sure is not the right answer. My issue is I do not know how to apply the exponents in the proper order to make this work. Any help you can give me on the details would be appreciated.
 
MurraySchwartz said:
I am having trouble understanding how to apply exponents to the following problem:


I = 1260/9.81*1.19[(2/1.19-1)(2/1.19+1)^(1.19+1/1.19-1)]^1/2

The answer I am getting is a tremendously huge number which I am sure is not the right answer. My issue is I do not know how to apply the exponents in the proper order to make this work. Any help you can give me on the details would be appreciated.
Click to expand...
You almost surely don't have all the parentheses you need to make the order of operations clear. When typing inline, you MUST separate numerators and denominators. For instance, where you have
1.19 + 1/1.19 - 1 = 1.030,
Do you REALLY mean
(1.19 + 1)/(1.19 - 1) = 11.53 ??

Show us step-by-step how you interpreted the order of operations.
 
Denis said:
As the Doc says...whadda heck is that? :confused:

Let x = 1.19 - 1 and y = 1.19 + 1
Your equation is now "less wieldy!":
I = 1260 / 9.81 * 1.19[(2 / x)(2 / y)^(y / x)]^1/2

Now clarify that with proper bracketing; like:
is 1260 divided by 9.81 .... then the multiplication
or
is 1260 divided by (9.91 * 1.19)....then the multiplication

also clarify what the 1st ^ does...
Click to expand...


Sorry I tried to make it simple and made it harder...My bad...Let's see if this helps clear it up...

Here is the original problem just as I got it....

I = (C/g) *y [(2/(y-1)) * (2/(y+1))(y+1)/(y-1)]1/2

Let C = 1,260
Let g = 9.81
Let y = 1.19
Solve for I

I am getting a really large number. I think because the exponent inside the brackets is coming out to be, by my calculations, 11.52...What it comes down to is I do not understand how, where when to apply the 1/2 exponent or the (y+1)/(y-1) exponent....I hope this is clearer.
 
Denis said:
~11.52 is correct (11.526315....)

Can't tell why you're getting such high results...calculator is kaput? :rolleyes:

p = (y+1)/(y-1)
Only (2/(y+1)) is taken to power p, right?

And (C/g) * y is same as 1 variable, right?
u = (C/g) * y
I = u * [(2/(y-1)) * (2/(y+1))^p]^(1/2)
Agree?

So we have:
p = 11.52632
u = 152.84404
2/(y-1) = 10.52632
2/(y+1) = .91324

I = 152.84404 * (10.52632 * .91324^11.52632)^(1/2) = 293.92154
Is that the book's answer?
Click to expand...

Denis: The book has 293.925....But you are a lot closer than I am :) Thanks for your help.
 
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