Answer to Question #128754 in Algebra for Lili

Question

Solve quadratic equation x² - x - 1 = 0

Answer 1

Solution

The problem can be solved using quadratic formula which state: x = $\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

the formula is for equations such as $ax^2+ bx + c = 0$

where in this problem x²−x−1= 0 

a=1, b=-1, c=-1

substituting a,b,and c in the quadratic formula we get;

x =$\frac{-(-1)\pm\ \ \sqrt{(-1)2-4(1)(-1)}}{2\times1}$

this gives out

x = $\frac{1\pm\ \ \sqrt{1\ +\ 4}}{2}$

therefore x =$\frac{1-\ \ \sqrt5}{2} or \frac{1\ +\ \ \sqrt5}{2}$

Hence x=−0.62 or x=1.62

Answer.

x=−0.62 or x=1.62