Question 980157

f(x)= 7/x + 7/x+4 such that f(x)= 1
So I set up the problem like this 1= 7/x + 7/x+4 and I get stuck. I'm supposed to solve using the quadratic formula. Help! 
<pre>{{{1 = 7/x + 7/(x + 4)}}} <-------- Good job up to here
{{{x(x + 4) = 7(x + 4) + 7x}}} --------- Multiplying by LCD: x(x + 4) 
{{{x^2 + 4x = 7x + 28 + 7x}}}
{{{x^2 + 4x - 7x = 14x + 28}}}
{{{x^2 + 4x - 14x - 28 = 0}}}
{{{x^2 - 10x - 28 = 0}}}
Solve the above trinomial for x, using the quadratic equation formula.