4MA0 Higher June 2016 Paper 4 Q19
19 Simplify \((7 + 2\sqrt{50})(5 - 2\sqrt{2})\)
Give your answer in the form \(a + b\sqrt{18}\) where \(a\) and \(b\) are integers.
Show your working clearly.
(3)
| Scheme | Marks |
|---|---|
Eg \(7 \times 5 - 7 \times 2 \times \sqrt{2} + 5 \times 2 \times \sqrt{50} - 2 \times 2 \times \sqrt{50} \times \sqrt{2}\) or \(35 - 14\sqrt{2} + 10\sqrt{50} - 4\sqrt{100}\) or \(35 - 14\sqrt{2} + 10\sqrt{50} - 40\) or \(35 - 14\sqrt{2} + 50\sqrt{2} - 20 \times 2\) | M1 |
| M1 | |
| \(-5 + 12\sqrt{18}\) | A1 |
| (3) |
Notes
M1: For brackets expanded correctly (need not be simplified)
M1: \(a = -5\) or \(b = 12\)
Dep on scoring the first M1
A1: Dep on M1