Question

X ^ 2 + 4x - 7 = 0 Solve using the Quadratic Formula

Answer 1

There's a special case of the quadratic formula called the Shakespeare Quadratic Formula (2b or -2b) that applies when the linear coefficient is even.

$x^2-2Bx + C \textrm{ has zeros }x = B \pm\sqrt{B^2 - C}$

If you're planning on solving a lot of quadratic equations quickly, it's good to know.

Here we have

$x^2 + 4x - 7 = 0$

so

$x = -2 \pm \sqrt{2^2 - -7}$

$x = -2 \pm \sqrt{11}$