The question shows that you are rigorously thinking about these concepts, which is good. Let's take a simple example which is similar in concept to those equations you've mentioned:
$\sqrt x = -1$
Because it is convenient, a generally agreed upon custom of mathematics is to denote a principal square root of a number by the $\sqrt{}$ symbol. For complex numbers, this is defined as follows (see wikipedia):
Let $x=ze^{i\varphi}$ where $\varphi$ is the principal angle ($\varphi\in(-\pi,\pi]$), then $\sqrt x = \sqrt z e^{i \varphi/2}=\sqrt z [\cos \tfrac \varphi 2 + i\sin \tfrac \varphi 2]$.
From this definition, we can see that the real part of $\sqrt x$ must be positive. Thus the equation $\sqrt x = -1$ has no solution in the complex numbers, when $\sqrt {}$ is taken to be the principal root. If we wanted to define a new number field for which $\sqrt x = -1$ has a solution, say $x=j$, then we would quickly run into trouble, as squaring both sides leads to the conclusion that $j=1$. Thus new rules would have to be created regarding how to treat the multiplication of square roots in our new number system, and very likely such a system would not end up being consistent.
In addition, such an extension does not yield as useful a result as the complex numbers, since we find that $x=1$ is a solution if we consider the multivalued square root function instead of the principal square root.
The complex numbers were introduced in order to create a field in which all algebraic equations had solutions. A good place to continue your investigation would be this thread: http://www.physicsforums.com/archive/index.php/t-315935.html
A small comment about why I dropped the $1=0$ approach: Now, although some equations may be able to be transformed to $1=0$, and thus the original equation was false within the given field, this is not reason in and of itself to dissuade one from an extension of the number system, such as the complex were to the reals. This was pointed out to me by Gerry Myerson in the comments above. To see why, consider a situation where the only number system is the reals, as it was before complex numbers were introduced. Now one may write an equation such as $x^2+1=0$ and use the following logic: $x^2>0 \implies x^2+1>1 \implies x^2+1\ne0$ and now, dividing our original equation by $x^2+1$ is valid, since $x^2+1\ne0$, and hence we have $1=0$.
So what we have shown is that, in $\mathbb R$, $x^2+1=0$ has no solution, but this did not prevent the extension of the reals to the complex numbers and so it should not serve as a reason to prevent an extension based on the equation $\sqrt x = -1$. Similarly to the way that the complex numbers made the inequality $x^2>0$ not true, our new number system would make the inequality $\sqrt x > 0$ not true.