JAMB 1986 · UME · Q21✱✱

Solve the equation $3x^2 + 6x - 2 = 0$ .

Worked solution (try it first)

Use the formula with $a = 3$ , $b = 6$ and $c = -2$ .
The discriminant is $b^2 - 4ac = 36 + 24 = 60$ .
So $x = \dfrac{-6 \pm \sqrt{60}}{6}$ .
Simplify the surd: $\sqrt{60} = \sqrt{4 \times 15}$
$= 2\sqrt{15}$ .
Divide each term by 6: $x = -1 \pm \frac{\sqrt{15}}{3}$ , option B.

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