1. Apr 17, 2008

### mercedesbenz

1. The problem statement, all variables and given/known data
28. What is the coefficient of $$x^{88}$$ from
$$(x+1)(x+2)(x-3)(x+4)(x+5)(x-6)...(x+88)(x+89)(x-90)$$.

29. Find x from this equation $$\frac{108}{\sqrt{x^2-2916}}=\frac{378-x-\sqrt{x^2-2916}}{x+54}$$.

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Apr 17, 2008

### tiny-tim

Hi mercedesbenz!

ok … a hint, as you asked for …

First, try answering: what are the coefficients of $$x^{90}$$ and of $$x^{89}$$ ?
You can simplify this slightly, before solving it:

Hint: what is √2916? What is 378/√2916?

3. Apr 18, 2008

### mercedesbenz

Thank you so much I've already solved it.