Question
Solve using formula.
5m2 – 4m – 2 = 0
5m2 – 4m – 2 = 0
✓
Answer
$\begin{array}{l}5 m^2-4 m-2=0 \text { compare with } a x^2+b x+c=0 \\ \Rightarrow a=5, b=-4 \text { and } c=-2 \\ \therefore b^2-4 a c=(-4)^2-4(5)(-2) \\ =16+40 \\ =56 \\ m=\frac{-b \pm \sqrt{b^2-4 a c}}{2 a} \\ \Rightarrow m=\frac{-(-4) \pm \sqrt{56}}{2 \times 5}\end{array}$
$\begin{array}{l}\Rightarrow m =\frac{4 \pm 2 \sqrt{14}}{10} \\ \Rightarrow m =\frac{4+2 \sqrt{14}}{10} \text { or } m =\frac{4-2 \sqrt{14}}{10} \\ \Rightarrow m =\frac{2+\sqrt{14}}{5} \text { or } m =\frac{2-\sqrt{14}}{5}\end{array}$
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