Question: The diagram shows the graph of $$y = x^2 - 5x - 3$$.
Use the graph to find estimates for the solutions of the simultaneous equations
$$y = x^2 - 5x - 3$$
$$y = x - 4$$
(3 marks)
$$x = , y =$$
or
$$x = , y =$$
1. **State the problem:** We need to find the points where the graphs of $$y = x^2 - 5x - 3$$ and $$y = x - 4$$ intersect.
2. **Set the equations equal:** Since both equal $$y$$, set them equal to find $$x$$:
$$x^2 - 5x - 3 = x - 4$$
3. **Rearrange to form a quadratic equation:**
$$x^2 - 5x - 3 - x + 4 = 0$$
$$x^2 - 6x + 1 = 0$$
4. **Use the quadratic formula:** For $$ax^2 + bx + c = 0$$, $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$.
Here, $$a=1$$, $$b=-6$$, $$c=1$$.
$$x = \frac{-(-6) \pm \sqrt{(-6)^2 - 4 \times 1 \times 1}}{2 \times 1} = \frac{6 \pm \sqrt{36 - 4}}{2} = \frac{6 \pm \sqrt{32}}{2}$$
5. **Simplify the square root:**
$$\sqrt{32} = \sqrt{16 \times 2} = 4\sqrt{2}$$
So,
$$x = \frac{6 \pm 4\sqrt{2}}{2} = 3 \pm 2\sqrt{2}$$
6. **Calculate approximate values:**
$$2\sqrt{2} \approx 2 \times 1.414 = 2.828$$
So,
$$x_1 = 3 + 2.828 = 5.828$$
$$x_2 = 3 - 2.828 = 0.172$$
7. **Find corresponding $$y$$ values using $$y = x - 4$$:**
For $$x_1 = 5.828$$:
$$y_1 = 5.828 - 4 = 1.828$$
For $$x_2 = 0.172$$:
$$y_2 = 0.172 - 4 = -3.828$$
8. **Final answers:**
$$x \approx 5.83, y \approx 1.83$$
or
$$x \approx 0.17, y \approx -3.83$$