x^2+7=0 this can be written as: x^2+0x+7=0 To solve using completer square we proceed as follows: x^2+0x=-7 but c=(b/2a)^2 c=(0/2*1)^2=0 hence x^2+0x+0=-7+0 this will be simplified as: x^2=-7 getting the square root of both sides gives us: sqrt(x^2)=sqrt(-7) x=+/-√-7 but √-1=i hence our answer will be: x=+/-7i
