Question

Check all of the correct solutions to this problem

Answer 1

To solve a quadratic equation $ax^2+bx+c=0$ we can use the quadratic formula:

$x_{1,2} = \cfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

In your case, the equation is identified by $a=c=1,\ b=-5$

So, the solving formula yields

$x_{1,2} = \cfrac{5\pm\sqrt{25-4}}{2} = \cfrac{5\pm\sqrt{21}}{2}$

So, the two solutions are derived by choosing the plus sign once, and the minus sign the other time:

$x_{1} = \cfrac{5+\sqrt{21}}{2},\quad x_{2} = \cfrac{5-\sqrt{21}}{2}$