4MA0 Higher June 2012 Paper 3 Q2
2 \[A = 2x^2 + kx\]
(a) \(x = -3\)
\(k = 4\)
Work out the value of \(A\). (2)
\(k = 4\)
Work out the value of \(A\). (2)
(b) \(A = 38\)
\(x = 4\)
Work out the value of \(k\). (3)
\(x = 4\)
Work out the value of \(k\). (3)
| Scheme | Marks |
|---|---|
| \(2 \times (-3)^2 + 4 \times (-3)\) or \(2 \times -3^2 + 4 \times -3\) or \(2 \times 9 - 4 \times 3\) or \(18 - 12\) or \(18 + -12\) | M1 |
| 6 | A1 |
| (2) |
Notes
M1: for substitution or for correct evaluation of either 18 or −12
A1: cao
Apart from Questions 9, 13, 18, 20 and 21 (where the mark scheme states otherwise) the correct answer, unless clearly obtained by an incorrect method, should be taken to imply a correct method.
| Scheme | Marks |
|---|---|
\(38 = 2 \times 4^2 + 4k\) or \((k) = \dfrac{A - 2x^2}{x}\) oe | M1 |
| \(4k = 38 - 32\) or \(4k = 6\) | M1 |
| 1.5 oe | A1 |
| (3) | |
| (Total 5 marks) |
Notes
M1: for correct substitution or rearrangement
M1: for correct rearrangement of correct substitution
SC M2 for \(\dfrac{38 - 32}{4}\)