u-2√2=3. please show work

Answer 1

What part of my work don't you understand?

u - √2 = 3

u - 1.414 = 3

u = 4.414

Answer 2

the answer should be 9

Answer 3

sorry. u-2√u=3

Answer 4

let x = sqrt u
then
x^2 - 2 x = 3
x^2 - 2 x - 3 = -
(x-3)(x+1) = 0
x = 3 or x = -1
try sqrt u = 3 then u = 9
9 - 6 = 3 Yes
try sqrt u = -3 , that is an imaginary number, forget it
so
u = 9