Question

Use the quadratic formula to determine the exact solutions to the equation. x2−2x−4=0

Answer 1

The quadratic formula 
$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$
for equation
$ax^2+bx+c=0$

In the given case
$x^2-2x-4=0$
a=1
b=-2
c=-4
Substitute in the quadratic equation
$x=\frac{-(-2)\pm\sqrt{(-2)^2-4(1)(-4)}}{2(1)}$
$=\frac{2\pm\sqrt{4+16}}{2}$
$= 1\pm\sqrt{5}$

Answer 2

The correct answer is:

1 + √5   or   1 - √5

i just took the test and these were the answers :)