x}^{2} - 9 \sqrt{2x - 4} " alt=" {x}^{2} - 9 \sqrt{2x - 4} " align="absmiddle" class="latex-formula"> for which value of x is this expression undefined?
When is smaller than , the resulting value under the square root will become negative. Since it is impossible to take the root of a negative number, the expression is thus undefined, however, it can be represented with the imaginary number where = .
