# Thread: need help solving for x

1. ## need help solving for x

i have a couple questions where im stuck at the part where i have to solve for x. these are the equations in which i need to solve for x

15x/(x^2 +14400)^(1/2) -10 = 0

and
4c(2x^2)+c(2x^2)+c(2880/x)+c(1440/x)
where i need to first solve for the derivative and then solve for x

2. Originally Posted by surffan
i have a couple questions where im stuck at the part where i have to solve for x. these are the equations in which i need to solve for x

15x/(x^2 +14400)^(1/2) -10 = 0

and
4c(2x^2)+c(2x^2)+c(288/x)+c(1440/x)
where i need to first solve for the derivative and then solve for x

$\displaystyle \frac{15x}{(x^2 +14400)^{\frac{1}{2}} }-10 = 0$

3. yes

4. $\displaystyle \frac{15x}{(x^2 +14400)^{\frac{1}{2}} }-10 = 0$

$\displaystyle \frac{15x}{(x^2 +14400)^{\frac{1}{2}} } = 10$

$\displaystyle \frac{15x}{\sqrt{x^2 +14400} } = 10$

$\displaystyle 15x = 10\sqrt{x^2 +14400}$

Squaring both sides

$\displaystyle 225x^2 = 100(x^2 +14400)$

Now expand right hand side, group like terms and solve.