1. **Solve the quadratic equation:** $12x^2 - 40 = 17x$ to 2 decimal places.
Step 1: Rewrite the equation in standard form:
$$12x^2 - 17x - 40 = 0$$
Step 2: Use the quadratic formula:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=12$, $b=-17$, and $c=-40$.
Step 3: Calculate the discriminant:
$$\Delta = (-17)^2 - 4 \times 12 \times (-40) = 289 + 1920 = 2209$$
Step 4: Find the square root of the discriminant:
$$\sqrt{2209} = 47$$
Step 5: Calculate the two solutions:
$$x_1 = \frac{17 + 47}{24} = \frac{64}{24} = 2.67$$
$$x_2 = \frac{17 - 47}{24} = \frac{-30}{24} = -1.25$$
Answer: $x = 2.67$ or $x = -1.25$.
2. **Find the points of intersection algebraically for the system:**
$$y = -x^2 + 6x - 5$$
$$y = -4x + 19$$
Step 1: Set the two expressions for $y$ equal to each other:
$$-x^2 + 6x - 5 = -4x + 19$$
Step 2: Rearrange to form a quadratic equation:
$$-x^2 + 6x - 5 + 4x - 19 = 0$$
$$-x^2 + 10x - 24 = 0$$
Multiply both sides by $-1$ for simplicity:
$$x^2 - 10x + 24 = 0$$
Step 3: Factor the quadratic:
$$(x - 6)(x - 4) = 0$$
Step 4: Solve for $x$:
$$x = 6 \quad \text{or} \quad x = 4$$
Step 5: Substitute back into $y = -4x + 19$ to find $y$ values:
For $x=6$:
$$y = -4(6) + 19 = -24 + 19 = -5$$
For $x=4$:
$$y = -4(4) + 19 = -16 + 19 = 3$$
Answer: Points of intersection are $(6, -5)$ and $(4, 3)$.
Quadratic Solve Intersection
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