OK, I'm going through my lab final - I'm having a difficult time with ALL OF IT...LOL Yes, I'm not good at higher math. And this is probably basic algebra....

My question is x-2x^1/2-3= 0 and use u substitution. My answer is x=9

Guest May 13, 2017

#1**+1 **

x- 2x^(1/2) - 3= 0

Let x = u^2 ...so.....x^(1/2) = u and we have

u^2 - 2u - 3 = 0 factor

(u - 3) ( u + 1) = 0 set both factors equal to 0 and solve

u - 3 = 0 u + 1 = 0

add 3 to both sides subtract 1 from both sides

u = 3 u = -1

So

u^2 = 3^2 = 9 = x or u^2 = (-1)^2 = 1 = x

The second solution makes the original problem false......so...... x = 9 is the only solution

CPhill
May 13, 2017