1MA0 Higher June 2016 Paper 2 Q20
20 Solve \(3x^2 + 6x - 2 = 0\)
Give your solutions correct to 2 decimal places. (3)
| Working | Answer | Mark | Notes |
|---|---|---|---|
| \(\dfrac{-6 \pm \sqrt{6^2 - 4 \times 3 \times -2}}{2 \times 3}\) \((x + 1)^2 - 1 - \frac{2}{3} = 0\) | 0.29 and −2.29 | 3 | M1 for substitution of \(a = 3\), \(b = 6\), \(c = -2\) into the formula or for completing the square (condone one sign error) M1 for \(\dfrac{-6 \pm \sqrt{60}}{6}\) or \(-1 \pm \sqrt{\dfrac{5}{3}}\) or in simplified form A1 for answers in the range 0.29 to 0.292 and \(-2.292\) to \(-2.29\) |