Specimen 2020 Paper 2 Q17
17 By multiplying both sides of the equation by \(x^{\frac{1}{2}}\)
Solve \(\quad 2x^{\frac{3}{2}} - 3x^{\frac{1}{2}} = 7x^{-\frac{1}{2}} \qquad\) for \(\quad x \gt 0\)
Give your answer to 3 significant figures.
You must show your working. [4 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(2x^2 - 3x = 7\) | M1 | at least two terms correct |
| \(2x^2 - 3x - 7\ (= 0)\) | A1 | oe 3-term quadratic equation |
| \(\dfrac{--3 \pm \sqrt{(-3)^2 - 4 \times 2 \times -7}}{2 \times 2}\) or \(\dfrac{3}{4} \pm \sqrt{\dfrac{65}{16}}\) | M1 | oe correct attempt to solve their 3-term quadratic equation |
| 2.77 | A1 | 2.77 and \(-1.27\) is A0 |