how to solve this problem

Question

-2x²+3=21

Answer 1

Hello, again Britt

 

-2x^2+3= 21              Subtract 3 from both sides

           -3   -3

-2x^2    =  18             Divide both sides by -2

   x^2    =  -9

You cannot take the square root of a negative number, but we can use complex numbers.  So, the square root -9 is +/-  3i

 

So, x= 3i 

 

I hope this helps. 

D.Y. T.