Question

Solve using formula.

x² – 3x – 2 = 0

Answer 1

 x² – 3x – 2 = 0
On comparing with the equation \[a x^2 + bx + c = 0\] 

a = 1, b = \[-3\] and c = \[-2\]

Now

\[b^2 - 4ac = \left( - 3 \right)^2 - 4 \times 1 \times \left( - 2 \right) = 9 + 8 = 17\]

\[x = \frac{- b \pm \sqrt{b^2 - 4ac}}{2a}\]

\[x = \frac{3 \pm \sqrt{17}}{2 \times 1} = \frac{3 \pm \sqrt{17}}{2}\]
\[\Rightarrow x = \frac{3 + \sqrt{17}}{2} \text{ or } x = \frac{3 - \sqrt{17}}{2}\]