4MA0 Higher January 2017 Paper 4R Q18
18 Here is the graph of \(\;y = x^3 - 0.2x^2 - 9x + 7\;\) for \(\;-4 \leqslant x \leqslant 3\)
(a) Use the graph to find an estimate for the solution of the equation \(\;x^3 - 0.2x^2 - 9x + 7 = -5\) (2)
(b) By drawing a suitable straight line on the grid, find an estimate for the solution of the equation \(\;x^3 - 0.2x^2 - 4x + 7 = 0\) (3)
| Scheme | Marks |
|---|---|
| M1 | |
| −3.4 | A1 |
| (2) |
Notes
M1: Line \(y = -5\) drawn or clear attempt to take reading at \(y = -5\)
A1: Accept −3.35 to −3.45 inclusive
| Scheme | Marks |
|---|---|
| M2 | |
| −2.5 | A1 |
| (3) | |
| (5 marks) |
Notes
M2: \(y = -5x\) drawn.
M1 for \(x^3 - 0.2x^2 - 9x + 7 = -5x\) or \(y = -5x\) oe
A1: dep on at least M1 (−2.45 – −2.55)