1. **State the problem:** Solve the simultaneous equations:
$$y = 2x^2 - 7$$
$$y = 3x + 20$$
2. **Set the equations equal to each other** since both equal $y$:
$$2x^2 - 7 = 3x + 20$$
3. **Rearrange the equation to standard quadratic form:**
$$2x^2 - 3x - 27 = 0$$
4. **Use the quadratic formula** to solve for $x$:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=2$, $b=-3$, and $c=-27$.
5. **Calculate the discriminant:**
$$b^2 - 4ac = (-3)^2 - 4 \times 2 \times (-27) = 9 + 216 = 225$$
6. **Find the square root of the discriminant:**
$$\sqrt{225} = 15$$
7. **Calculate the two possible values for $x$:**
$$x = \frac{-(-3) \pm 15}{2 \times 2} = \frac{3 \pm 15}{4}$$
8. **First solution:**
$$x = \frac{3 + 15}{4} = \frac{18}{4} = \frac{9}{2} = 4.5$$
9. **Second solution:**
$$x = \frac{3 - 15}{4} = \frac{-12}{4} = -3$$
10. **Find corresponding $y$ values by substituting back into $y = 3x + 20$:**
For $x=4.5$:
$$y = 3(4.5) + 20 = 13.5 + 20 = 33.5$$
For $x=-3$:
$$y = 3(-3) + 20 = -9 + 20 = 11$$
**Final solutions:**
$$(x, y) = \left(4.5, 33.5\right) \text{ and } (-3, 11)$$
Simultaneous Equations A8F304
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