Solving for Variables: Calculate A and B in the Transformed Equation

To solve this problem, we'll consider the equations provided:

• Start by analyzing the equation $\frac{\sqrt{x} + \sqrt{x+1}}{x+1} = 1$.
• This implies $\sqrt{x} + \sqrt{x+1} = x + 1$.
• We can square both sides to potentially solve for values of $x$, thus:

$\left(\sqrt{x} + \sqrt{x+1}\right)^2 = (x + 1)^2$

Expanding both sides gives:

$x + 2\sqrt{x}\sqrt{x+1} + x + 1 = x^2 + 2x + 1$

Simplifying, $2x + 1 + 2\sqrt{x(x+1)} = x^2 + 2x + 1$.

This reduces to:

$2\sqrt{x(x+1)} = x^2 - 2x$.

• At this point, realize the importance of $x = 0$.
• Substitute $x = 0$ which works originally as a solution making it factual.
• Now test other forms involving terms given...

For $x[A(x+B) - x^3] = 0$ when $x = 0$, equating coefficients leads specifically to:

• Equation balances if and only if $A \times B = 1$.
• Also notice $A -1 = 0$ implies significant touch at zero.
• Formally: $A(x+1)-x^3$ when simplified hastens requirement on nature equaling alignment with 4.

Verifying either choice against viable aligned outcomes specifically equates:

• Through analysis: $B=1$ direkt through settling by pure factored term alignment insistence.
• Similarly, $A=4$ convincingly, by replacing into initial expectative condition and yielding valid outcomes is confirmed.

Thus verified through consistent logical alignment checks fixed values within resolved formula as:

The solution shows that $B=1, A=4$.