Which method do you use to solve the quadratic equation #81x^2+1=0#?

1 Answer
Nov 3, 2014

I would try to isolate #x#.

#81x^2+1=0#

by subtracting 1,

#=> 81x^2=-1#

by dividing by 81,

#=> x^2=-1/81#

Since #x^2# can never be negative for a real number #x#, the equation has no real solutions; however, if you are looking for its complex solutions, then by taking the square-root,

#=> x=pmsqrt{-1/81}=pm i/9 #


I hope that this was helpful.