u-2√u=3. what is u?

Answer 1

change u to x^2, then sqrtu = x

x^2-2x-3=0

(x-3)(x+1)=0

x=3, or u= + 9

x=-1, or u=+ 1

checking
u=9
9-2*3=3 checks
u= i
1-2 does not equal 3, does not check.