Chapter 9 - Quadratic Functions and Equations - 9-6 The Quadratic Formula and the Discriminant - Practice and Problem-Solving Exercises - Page 587: 39

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$$ \text{The quadratic formula is given by:}$$ $$ x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$$ $$ \text{Plugging in the given values:}$$ $$a=1, b=-4, c=4$$ $$ x = \frac{--4 \pm \sqrt{-4^2-4(1)(4)}}{2(1)}$$ $$\text{Reducing within the radical gives: } $$ $$ x = \frac{--4 \pm \sqrt{0}}{(2)1}$$ $$ \text {This gives: } $$ $$x=2$$