How do you solve $x(2x+1)=-4$ using the quadratic formula?

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Answer 1 · 2017-07-17T22:43:13

We must get the equation into the form of $ax^2+bx+c=0$

$x(2x+1)=-4 iff 2x^2+x+4=0$

So now $a=2, b=1, c=4$

from the formula we know

$x=(-b+-sqrt(b^2-4ac))/(2a)=(-1+-sqrt(1-32))/4$

so we see that the equation has no real solutions, but it has comple ones.

which are

$x=-1/4+-isqrt(31/16$

How do you solve x(2x+1)=-4x(2x+1)=-4 using the quadratic formula?