1. **State the problem:** Find the vertex, y-intercept, and x-intercepts of the quadratic function $$y = 4x^2 - 8x - 5$$.
2. **Rewrite the quadratic in vertex form:**
Start by factoring out 4 from the first two terms:
$$y = 4(x^2 - 2x) - 5$$
3. **Complete the square inside the parentheses:**
Take half of the coefficient of $x$, which is $-2$, half is $-1$, square it to get $1$.
Add and subtract $1$ inside the parentheses:
$$y = 4(x^2 - 2x + 1 - 1) - 5 = 4((x - 1)^2 - 1) - 5$$
4. **Simplify:**
$$y = 4(x - 1)^2 - 4 - 5 = 4(x - 1)^2 - 9$$
5. **Identify the vertex:**
The vertex form is $$y = a(x - h)^2 + k$$ where vertex is $(h, k)$.
Here, vertex is at $$ (1, -9) $$.
6. **Find the y-intercept:**
Set $$x = 0$$:
$$y = 4(0)^2 - 8(0) - 5 = -5$$
So y-intercept is $$ (0, -5) $$.
7. **Find the x-intercepts:**
Set $$y = 0$$:
$$0 = 4x^2 - 8x - 5$$
Divide both sides by 4:
$$0 = \cancel{4}x^2 - \cancel{4}2x - \cancel{4}\frac{5}{4}$$
$$0 = x^2 - 2x - \frac{5}{4}$$
Use quadratic formula:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ with $$a=1$$, $$b=-2$$, $$c=-\frac{5}{4}$$.
Calculate discriminant:
$$b^2 - 4ac = (-2)^2 - 4(1)(-\frac{5}{4}) = 4 + 5 = 9$$
Calculate roots:
$$x = \frac{2 \pm \sqrt{9}}{2} = \frac{2 \pm 3}{2}$$
So,
$$x_1 = \frac{2 + 3}{2} = \frac{5}{2} = 2.5$$
$$x_2 = \frac{2 - 3}{2} = \frac{-1}{2} = -0.5$$
Thus, x-intercepts are $$\left(2.5, 0\right)$$ and $$\left(-0.5, 0\right)$$.
**Final answers:**
- Vertex: $$(1, -9)$$
- Y-intercept: $$(0, -5)$$
- X-intercepts: $$(2.5, 0)$$ and $$(-0.5, 0)$$
Quadratic Vertex 6F141A
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.