# Help solving disequality and functions domain

• November 18th 2011, 04:48 AM
prankster
Help solving disequality and functions domain
Can you show me the solutions (possibly step-by-step) of these problems?

1) Calculate the domain of the function:
$\lg{\left( \frac{1+2\cos x}{1 - 2\sin x}\right)}$

2) Calculate the domain of the function:
$\sqrt{\frac{\lg x +1}{\lg x + 3}}$

3) Find the solutions of the inequality:
$\frac{2\times 3^x + 1}{3^{x+1} -1} > 1$

• November 18th 2011, 05:12 AM
HallsofIvy
Re: Help solving disequality and functions domain
Do you know what "domain" means? Is so what do you know about the domains of the logarithm and square root functions?

Do you know what happens if you mutliply both sides of an inequality by a negative number? Do you know the "laws of exponents".