Question

Solve using the quadratic formula. x2 - x - 1 = 0

Answer 1

Answer: $\begin{gathered} x\text{ = }\frac{1\pm\sqrt{5\text{ }}}{2}\text{ \lparen2nd option\rparen} \\ \end{gathered}$

Explanation:

Given:

$x^2\text{ - x - 1 = 0}$

To find:

To find x using a quadratic function

The quadratic formula is given as:

$x\text{ = }\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}$$\begin{gathered} a\text{ = 1, b = -1, c =-1} \\ \\ \\ x\text{ = }\frac{-(-1)\pm\sqrt{(-1)^2-4(1)(-1)}}{2(1)} \\ \\ x\text{ = }\frac{1\pm\sqrt{1+4}}{2} \end{gathered}$$\begin{gathered} x\text{ = }\frac{1\pm\sqrt{5\text{ }}}{2}\text{ \lparen2nd option\rparen} \\ \end{gathered}$