Please help (quadratic formula)
@Mimi_x3
Can you find a copy of the quadratic formula and post it?
\[-b \pm \sqrt{b^2-4ac}/2a\]
The 2a denominator is below the entire expression before it.
Now simply use 5 for a, 3 for b, and -2 for c in the quadratic formula. Then simplify the expression.
2/5
\(k = \dfrac{-\color{red}{b} \pm \sqrt{\color{red}{b}^2 - 4\color{green}{a}\color{purple}{c}}}{2\color{green}{a}}\) \(\color{green}{a = 5}\) \(\color{red}{b = 3}\) \(\color{purple}{c = -2}\) \(k = \dfrac{-\color{red}{3} \pm \sqrt{\color{red}{3}^2 - 4(\color{green}{5})(\color{purple}{-2})}}{2(\color{green}{5})}\)
\(k = \dfrac{-3 \pm \sqrt{9 - (-40)}}{10}\) \(k = \dfrac{-3 \pm \sqrt{49}}{10}\) \(k = \dfrac{-3 \pm 7}{10}\) Did you get to this point?
yes
Good. Now you need to know what to do with the \(\pm\).
After you simplify the solution as much as possible while you still have the \(\pm\), you need to turn it into two equations, one for the + case, and one for the - case. The two equations are separated by the word "or."
\(k = \dfrac{-3 \pm 7}{10}\) \(k = \dfrac{-3 + 7}{10}\) or \(k = \dfrac{-3 -7}{10}\) Now you solve each equation above and always kep the word "or" in between them.
\[\frac{ -3-7 }{ 10 }=-1\]
\[\frac{ -3+7 }{ 10 }=\frac{ 2 }{ 5 }\]
\(k = \dfrac{-3 + 7}{10}\) or \(k = \dfrac{-3 - 7}{10}\) \(k = \dfrac{4}{10}\) or \(k = \dfrac{-10}{10}\) \(k = \dfrac{2}{5}\) or \(k = -1\)
You are correct. Those two solutions are correct.
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