For this case we have the following quadratic equation:
[tex]x ^ 2 + 81 = 0[/tex]
We look for the solutions:
We subtract 81 from both sides of the equation:
[tex]x ^ 2 = -81[/tex]
We apply square root on both sides to eliminate the exponent:
[tex]x = \pm \sqrt {-81}\\x = \pm ((\sqrt {-1} * \sqrt {81})[/tex]
We have to:
[tex]\sqrt {81} = 9\\\sqrt {-1} = i[/tex]
So:
[tex]x_ {1} = + 9i\\x_ {2} = - 9i[/tex]
ANswer:
Two imaginary solutions
