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49

answers:

2
Q: 

Solve for Variable 'g' i.e. Simplify Equation

Can someone help me simplify this expression for a Civil Engineering application? I had a quick answer here to some logical operations earlier, so I thought I would give it a try...

d=(g-h)*0.5/2*h + (g-l)*0.5/2*l + (L - (g-h)*0.5/2 - (g-l)*0.5/2) * g

where d=2.67; h=0.04; l=0.03; and L=28.4

I can't simplify the equation to isolate 'g' though I got this far

+1  A: 

In each term where you have (g-X)Y for some expressions X and Y, factor this into gY-XY. Eliminate the parentheses of the third term. Then factor out g.

David M.  2010-09-07 23:38:02
I got to here: d+.25h^2 + .25l^2 = Lg -.5g^2 but I am stuck with the right side binomial I think...
Stephen  2010-09-07 23:58:47
You can use the quadratic formula. But it'd probably be smarter to go with Wolfram Alpha; why didn't I think of that? (In particular, a naive implementation of the quadratic formula is subject to loss of precision for certain inputs.)
David M.  2010-09-08 00:07:53
+3  A: 

Wolfram alpha has no trouble solving it.

g is approximately 56.7759 (assuming I substituted correctly).

Macsyma/Maxima, Maple, Mathematica, or any other CAS would also help you if you need answers and not solutions.

Paul McMillan  2010-09-07 23:43:59
You are right, but there are actually two subproblems resulting from the square and I needed the other answer which was -0.093873026...ultimately it had to do with perfect squares that popped up from the reduction to 2*(d+.25h^2)=g^2 -g2L
Stephen  2010-09-08 00:33:01

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