1. Problem: Find the product function $(fg)(x)$ where $f(x) = 4x - 2$ and $g(x) = 2x + 2$.
Step 1: Recall that $(fg)(x) = f(x) \cdot g(x)$.
Step 2: Substitute the given functions:
$$ (fg)(x) = (4x - 2)(2x + 2) $$
Step 3: Expand the product:
$$ = 4x \cdot 2x + 4x \cdot 2 - 2 \cdot 2x - 2 \cdot 2 $$
$$ = 8x^2 + 8x - 4x - 4 $$
Step 4: Simplify like terms:
$$ 8x^2 + 4x - 4 $$
Answer: $(fg)(x) = 8x^2 + 4x - 4$
2. Problem: Find $(2f + 3g)(1)$ where $f(x) = 5x - 2$ and $g(x) = 4 - 3x$.
Step 1: Compute $2f(x) + 3g(x)$:
$$ 2f(x) + 3g(x) = 2(5x - 2) + 3(4 - 3x) $$
$$ = 10x - 4 + 12 - 9x $$
$$ = (10x - 9x) + (-4 + 12) $$
$$ = x + 8 $$
Step 2: Evaluate at $x=1$:
$$ 1 + 8 = 9 $$
Answer: $(2f + 3g)(1) = 9$
3. Problem: Given $f(x) = \sqrt{25 - x^2}$ and $g(x) = \sqrt{x} + 4$, find:
A. Domain of $(fg)(x)$
B. Domain of $\left(\frac{f}{g}\right)(x)$
C. Domain of $\left(\frac{g}{f}\right)(x)$
Step 1: Find domain of $f(x)$:
$$ 25 - x^2 \geq 0 \implies x^2 \leq 25 \implies -5 \leq x \leq 5 $$
Step 2: Find domain of $g(x)$:
$$ x \geq 0 $$ (since $\sqrt{x}$ requires $x \geq 0$)
Step 3: Domain of $(fg)(x) = f(x) \cdot g(x)$ is intersection of domains of $f$ and $g$:
$$ [0,5] $$
Step 4: Domain of $\left(\frac{f}{g}\right)(x)$ requires $g(x) \neq 0$ and $x$ in domain of both $f$ and $g$.
Since $g(x) = \sqrt{x} + 4 > 0$ for all $x \geq 0$, no zeros.
So domain is $[0,5]$.
Step 5: Domain of $\left(\frac{g}{f}\right)(x)$ requires $f(x) \neq 0$ and $x$ in domain of both.
$f(x) = 0$ when $25 - x^2 = 0 \implies x = \pm 5$.
Within $[0,5]$, $f(5) = 0$, so exclude $x=5$.
Domain is $[0,5)$.
Answer:
A. Domain of $(fg)(x)$ is $[0,5]$
B. Domain of $\left(\frac{f}{g}\right)(x)$ is $[0,5]$
C. Domain of $\left(\frac{g}{f}\right)(x)$ is $[0,5)$
4. Problem: Given relation $R = \{(x,y): y \leq x - 2 \text{ and } y \geq 2x - 4\}$
A. Sketch the graph of $R$ (description only)
B. Find domain of $R$
C. Find range of $R$
Step 1: The relation is the set of points between two lines:
$$ y \leq x - 2 $$
$$ y \geq 2x - 4 $$
Step 2: Find intersection of the lines:
$$ x - 2 = 2x - 4 $$
$$ -2 + 4 = 2x - x $$
$$ 2 = x $$
$$ y = 2 - 2 = 0 $$
Intersection point is $(2,0)$.
Step 3: Domain is all $x$ values where the region exists.
Since $y$ is between two lines, and the lines intersect at $x=2$, check behavior:
For $x < 2$, $2x - 4$ is less than $x - 2$, so region exists.
For $x > 2$, $2x - 4$ is greater than $x - 2$, so no points satisfy both inequalities.
Therefore, domain is $(-\infty, 2]$.
Step 4: Range is $y$ values between the two lines over the domain.
At $x=2$, $y=0$.
As $x \to -\infty$, $x - 2 \to -\infty$ and $2x - 4 \to -\infty$, so range is $(-\infty, 0]$.
Answer:
A. Region between lines $y \leq x - 2$ and $y \geq 2x - 4$ for $x \leq 2$.
B. Domain: $(-\infty, 2]$
C. Range: $(-\infty, 0]$
5. Problem: For $g(x) = -2x^2 + 6x$, find vertex, line of symmetry, max/min value, and range.
Step 1: Identify $a = -2$, $b = 6$, $c = 0$.
Step 2: Vertex $x$-coordinate:
$$ x = -\frac{b}{2a} = -\frac{6}{2 \times -2} = -\frac{6}{-4} = 1.5 $$
Step 3: Vertex $y$-coordinate:
$$ g(1.5) = -2(1.5)^2 + 6(1.5) = -2(2.25) + 9 = -4.5 + 9 = 4.5 $$
Vertex is $(1.5, 4.5)$.
Step 4: Since $a = -2 < 0$, parabola opens downward, so vertex is maximum.
Step 5: Line of symmetry is $x = 1.5$.
Step 6: Maximum value is $4.5$.
Step 7: Range is $(-\infty, 4.5]$.
Answer:
Vertex: $(1.5, 4.5)$
Line of symmetry: $x = 1.5$
Maximum value: $4.5$
Range: $(-\infty, 4.5]$
6. Problem: Given vertex of $g(x) = x^2 + bx + c$ is $(6, -1)$, find $b$.
Step 1: Vertex formula:
$$ x = -\frac{b}{2a} $$
Since $a=1$,
$$ 6 = -\frac{b}{2} \implies b = -12 $$
Answer: $b = -12$
7. Problem: Rewrite $g(x) = x^2 - 12x + 5$ in vertex form $a(x - h)^2 + k$ and sketch.
Step 1: Complete the square:
$$ g(x) = x^2 - 12x + 5 $$
$$ = (x^2 - 12x + 36) - 36 + 5 $$
$$ = (x - 6)^2 - 31 $$
Answer: $g(x) = (x - 6)^2 - 31$
Vertex at $(6, -31)$, parabola opens upward.
Slug: "function operations"
Subject: "algebra"
Desmos: {"latex":"y=(4x-2)(2x+2)","features":{"intercepts":true,"extrema":true}}
q_count: 7
Function_Operations
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