Question

Solve using formula.

3m² + 2m – 7 = 0

Answer 1

 3m² + 2m – 7 = 0
On comparing with the equation  \[a x^2 + bx + c = 0\]

a = 3, b = 2 and c =  \[-7\]  

Now

\[b^2 - 4ac = \left( 2 \right)^2 - 4 \times 3 \times \left( - 7 \right) = 4 + 84 = 88\]

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

\[x = \frac{- 2 \pm \sqrt{88}}{2 \times 3}\]

= \[\frac{- 2 \pm \sqrt{4 \times22}}{6}\]

= \[\frac{- 2 \pm 2\sqrt{22}}{6}\]

= \[\frac{2(- 1 \pm\sqrt{22})}{6}\]

= \[\frac{- 1 \pm\sqrt{22}}{3}\]

\[ \Rightarrow x = \frac{- 1 + \sqrt{22}}{3} \text{ or } \frac{- 1 - \sqrt{22}}{3}\]