Complex/Imaginary Numbers

[heya27]

Solve the equation 4x^2+5=-7
Solve the equation 4x^2=20=0

And how do I get the answer so I can write it in standard form?

 

[pka]

Solve the equation 4x^2+5=-7
Solve the equation 4x^2=20=0

If \(\displaystyle 4x^2+5=-7\) then \(\displaystyle x^2=-3\)
So \(\displaystyle x=\pm\sqrt{3}\,\mathif{i}\).