A root of x2 – 5x – 1 = 0 is

[tex]x^2-5x-1=0\\\\ a=1,\ b=-5,\ c=-1\\\\ \Delta=b^2-4ac=(-5)^2-4*1*(-1)=25+4=29\\\\ \sqrt{\Delta}=\sqrt{29}\\\\ x_1=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-\sqrt{29}}{2*1}=\frac{5-\sqrt{29}}{2}\\\\ x_2=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{29}}{2*1}=\frac{5+\sqrt{29}}{2}\\ [/tex]

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Louli Louli · Answer 2 · 2018-08-10T08:05:00-04:00

Answer:

The roots are [tex] \frac{5+\sqrt{29}}{2} [/tex] and [tex] \frac{5-\sqrt{29}}{2} [/tex]

Explanation:

The general form of the quadratic equation is:

ax² + bx + c = 0

The given equation is:

x² - 5x - 1 = 0

By comparison:

a = 1

b = -5

c = -1

To get the roots of the equation, we will use the quadratic formula shown in the attached image.

This means that:

either [tex] x = \frac{5+\sqrt{(-5)^2-4(1)(-1)}}{2(1)} = \frac{5+\sqrt{29}}{2} [/tex]

or [tex] x = \frac{5-\sqrt{(-5)^2-4(1)(-1)}}{2(1)} = \frac{5-\sqrt{29}}{2} [/tex]

Hope this helps :)