Answer:
The answer to your question is: the third option
Step-by-step explanation:
x² + 5x = - 1
x² + 5x + [tex](\frac{5}{2}) ^{2}[/tex] = -1 + [tex](\frac{5}{2} )^{2}[/tex]
(x + [tex]\frac{5}{2}[/tex])² = - 1 + 25/4
(x + [tex]\frac{5}{2}[/tex])² = (-4 + 25) / 4
(x + [tex]\frac{5}{2}[/tex])² = 21/4
(x + [tex]\frac{5}{2}[/tex]) = ± [tex]\sqrt{\frac{21}{4} }[/tex]
x = [tex]\frac{5}{2} ± \frac{\sqrt{21}}{2}[/tex]
x = [tex]\frac{-5 ± \sqrt{21} }{2}[/tex]
