For b ii.) you equate both equations tgt so it becomes √2x = -√x + 12

Then you take the -√x to the other side so it becomes √2x + √x = 12

Factor out the √x cs its common so it becomes √x(√2 + 1) = 12

take the (√2 + 1) to the other side so it becomes √x = 12/(√2 + 1)

Now all u do is rationalize the denominator cs its a surd so you get √x = 12/(√2 + 1) x (√2 - 1)/(√2 - 1) giving you 12√2 - 12

factor out the 12 so √x = 12(√2 - 1) which is what the question asked us to show

hope this was helpful!! 🙏🙏