Question 7807
When you write problems such as this one, you need write them in a way as to leave no question about what the problem is asking. Using parentheses is one way to do this.

You wrote:
 5sqrt(x) - sqrt(x) - 1 = 6  or is it 5sqrt(x) - sqrt(x-1) = 6 ?

I'll assume that it is the first one:

 {{{5sqrt(x) - sqrt(x) - 1 = 6}}} Subtract the sqrt terms.

{{{4sqrt(x) - 1 = 6}}} Now add 1 to both sides.

{{{4sqrt(x) = 7}}} Divide both sides by 4.

{{{sqrt(x) = 7/4}}} Finally, square both sides.

{{{x = 49/16}}} 

{{{x = 3.0625}}}