Moderate -0.8 This is a straightforward simultaneous equations problem requiring substitution of y = 11 - 2x into xy = 12, leading to a simple quadratic. It's more routine than average A-level questions since it involves only basic algebraic manipulation with no conceptual challenges or multi-step reasoning.
Solution of quadratic \(\rightarrow (1\frac{1}{2},8)\) and \((4,3)\)
M1, A1, DM1, A1
Complete elimination of \(x\), or of \(y\). Correct quadratic. Correct method of solution \(\rightarrow\) 2 values. All correct (guesswork or TI B1 for one pair of values, full marks for both).
$x(11-2x) = 12$
$2x^2-11x+12=0$
Solution of quadratic $\rightarrow (1\frac{1}{2},8)$ and $(4,3)$ | M1, A1, DM1, A1 | Complete elimination of $x$, or of $y$. Correct quadratic. Correct method of solution $\rightarrow$ 2 values. All correct (guesswork or TI B1 for one pair of values, full marks for both).