Question
Solve using formula.
3m2 + 2m – 7 = 0
3m2 + 2m – 7 = 0
✓
Answer
$\begin{array}{l}3 m ^2+2 m -7=0 \text { compare with } ax ^2+ bx + c =0 \\ \Rightarrow a =3, b =2 \text { and } c =-7 \\ \therefore b ^2-4 ac =2^2-4(3)(-7) \\ =4+84 \\ =88 \\ m =\frac{- b \pm \sqrt{ b ^2-4 ac }}{2 a } \\ \Rightarrow m =\frac{-2 \pm \sqrt{88}}{2 \times 3}\end{array}$
$\begin{array}{l}\Rightarrow m =\frac{-2 \pm \sqrt{88}}{6} \\ \Rightarrow m =\frac{-2+2 \sqrt{22}}{6} \text { or } m =\frac{-2-2 \sqrt{22}}{6} \\ \Rightarrow m =\frac{-1+\sqrt{22}}{3} \text { or } m =\frac{-1-\sqrt{22}}{3}\end{array}$
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