x² +5x+1 =0 it's a quadratic equation of the form: ax²+bx+c=0
Solving this equation is finding the roots of this equation to that end we use the following formula:
x' =[-b+√(b²-4ac)]/2a & x"=[-b-√(b²-4ac)]/2a
Now replace a, b & c by their respective values:
a=1, b=5 & c=1
& you will find
x' =(-5+√21√)/2 or x'=-0.208
& x" =(-5-√21)/2 or x" =-4.79