Stuck on simple Maths Question

SilverKrest · 23-04-2014 3:48pm #1

Completely stuck on this question. Does anyone know the steps. Any help appreciated.

Find an expression for b given:
0.0505=f[(0.09/b^2)/(2*9.81)]

The answer is: b=0.38f^(1/5)

Just cant reach this answer

Yakuza · 23-04-2014 4:53pm

Does f[] describe a function or is f just multiplied by the term in square braces?[] If f is a function, please add f[x] to the problem.
Can you use Latex or upload a scan of the original question, as your notation isn't very clear.

At a wild guess, is it some form of applied maths or mechanics question (assuming the 9.81 refers to g, the acceleration due to gravity)?

SilverKrest · 23-04-2014 8:34pm

The f is multiplied by the bracket. Yes it is gravity. And apologies but I'm not allowed to upload images as I've too few posts on this

SilverKrest · 23-04-2014 9:28pm

Have the correct format now.
Here is question: http://www.hostmath.com/Show.aspx?Code=0.0505=f(\frac{\frac{0.09}{b^{2}}}{2\times9.81})

And here is answer: http://www.hostmath.com/Show.aspx?Code=b=0.38f

SilverKrest · 23-04-2014 9:35pm

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Edit: the f should be also to the power of a fifth (in the answer link)

dlouth15 · 23-04-2014 9:43pm

Here are some suggested steps.

1. Simplify the right hand side so you don't have two divisions.

2. Rearrange so that the [latex]b^2[/latex] is on the left hand side and the 0.0505 is on the RHS. Basically swap the two.

3. Take the sqrt of both sides so you have b on the LHS and a an expression involving numbers times [latex]f^{1/2}[/latex] on the RHS.

Here is the first step:

[latex]\displaystyle{0.0505 = f\left(\frac{\left(\frac{0.09}{b^{2}}\right)}{2\left(9.81\right)}\right)=\frac{0.09}{2\left(9.81\right)b^{2}}\times f[/latex]

Btw, I don't get [latex] b=0.38f^{1/5}[/latex]. I don't think the answer is correct. Are you sure it is [latex]b^2[/latex] in the question.

Stuck on simple Maths Question

Comments