Quadratic Formula:
[tex] \boxed{ \bf{x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}}}[/tex]
Given Quadratic Equation:
x² + x - 1 = 0
a = 1 (Quadratic coefficient)
b = 1 (Linear coefficient)
c = -1 (Constant coefficient)
By substituting values in the formula, we get:
[tex] \rm \longrightarrow x = \dfrac{-1 \pm \sqrt{1^2 - 4(1)( - 1)}}{2 \times 1} \\ \\ \rm \longrightarrow x = \dfrac{ - 1 \pm \sqrt{1 + 4} }{2} \\ \\ \rm \longrightarrow x = \dfrac{ - 1 \pm \sqrt{5} }{2} [/tex]
