If you stand on a ship in a calm sea, then your height x (in feet) above sea level is related to the farthest distance y (in miles) that you can see by the equation:
y=sqrt (1.5x+(x/5280)^2)
how high up do you have to be to be able to see 10mi?

Question

If you stand on a ship in a calm sea, then your height x (in feet) above sea level is related to the farthest distance y (in miles) that you can see by the equation:
y=sqrt (1.5x+(x/5280)^2)
how high up do you have to be to be able to see 10mi?

jamesj · Answer

So you want to solve for x when y = 10

anonymous · Answer

right. so plug 10 in for y. the way i tried it was then to subtract 10 from both sides to get it set to 0 but when I solve it i get a negetive number

jamesj · Answer

No, you have
$$ 10 = \sqrt{stuff} $$
Square roots are always nasty. The first step is to square both sides. Then you will have a quadratic equation in x.

anonymous · Answer

so 100=1.5x+(x/5280)^2 then what?

jamesj · Answer

Now you have a quadratic equation in x. Use your good ol' quadratic formula.

jamesj · Answer

stuff.x^2 + stuff.x + stuff = 0

anonymous · Answer

so..(x/5280)^2 would be my a?
That fraction is just confusing me