(a) Copy and complete the table of values for the relation (y = 5 – 7x – 6x^{2}) for (-3 leq x leq 2).
| x | -3 | -2 | -1 | -0.5 | 0 | 1 | 2 |
| y | -28 | 6 | 5 |
(b) Using a scale of 2cm to 1 unit on the x- axis and 2cm to 5 units on the y- axis, draw the :
(i) graph of (y = 5 – 7x – 6x^{2}) ; (ii) line (y = 3) on the same axis.
(c) Use your graph to find the : (i) roots of the equation (2 – 7x – 6x^{2} = 0) ; (ii) maximum value of (y = 5 – 7x – 6x^{2}).
Explanation
| x | -3 | -2 | -1 | -0.5 | 0 | 1 | 2 |
| y | -28 | -5 | 6 | 7 | 5 | -8 | -33 |
(b)(i)
(c)(i) (2 – 7x – 6x^{2} = 0)
(2 + 3 – 7x – 6x^{2} = 3)
(5 – 7x – 6x^{2} = 3)
(therefore text{the roots at y = 3 are } x = -1.4; 0.2)
(ii) Maximum value of (y = 5 – 7x – 6x^{2}) is y = 7.