81st Problem 2016

Algebra Level 2

Solve for $x$ :

$-{ x }^{ 2 }+x-4=0$

Check out the set: 2016 Problems

\dfrac {1 \pm \sqrt {-17}}{2}

\dfrac {1 \pm \sqrt {17}}{2}

\dfrac {1 \pm \sqrt {-15}}{2}

\dfrac {1 \pm \sqrt {15}}{2}

1 solution

Hung Woei Neoh
Jun 12, 2016

Use the quadratic formula:

$-x^2+x-4 = 0\\ x^2-x+4=0\\ x=\dfrac{-(-1) \pm \sqrt{(-1)^2 - 4(1)(4)}}{2(1)}\\ =\dfrac{1 \pm \sqrt{1-16}}{2}\\ =\boxed{\dfrac{1 \pm \sqrt{-15}}{2}}$