The collocation method is to unify the left and right sides of the function, and the unified factor is the polynomial in parentheses of the function. Therefore, the polynomial in function brackets is regarded as a whole, and the polynomial on the right can be reduced to the sum of polynomials containing only it.

In this example, (√x- 1) is regarded as a whole, and (x+2√x) can be reduced to the sum of polynomials containing only (√x- 1).

X+2 √ x = x-2 √ x+1+4 √ x-4+3 = (√X- 1) 2+4 (√ x-1)+3 constant term can be regarded as (√ x-/kloc-0.

So you can

f(√x- 1)=(√x- 1)^2+4(√x- 1)+3

That is f (x) = x 2+4x+3.

Determination of definition domain

Because x-1>; =- 1

So the domain of the function is-1, which is positive infinity.