Calculus Assignment
1. Solve the inequalities and equations:
I. Solve \(|2x + 3| \leq |2x + 1|\)
1. Consider cases based on sign of expressions inside absolute values.
2. For \(2x + 3 \geq 0\) and \(2x + 1 \geq 0\), solve normally.
3. For each case, square both sides if needed or separate into subcases.
II. Solve \(|x - 3| \leq 4\)
1. This means \(-4 \leq x-3 \leq 4\).
2. Add 3 to all parts: \(-1 \leq x \leq 7\).
III. Solve \(\frac{x^2 - 3x - 54}{x^2 - 5x - 14} \geq 0\)
1. Factor numerator: \(x^2 - 3x - 54 = (x - 9)(x + 6)\).
2. Factor denominator: \(x^2 - 5x - 14 = (x - 7)(x + 2)\).
3. The expression is \(\frac{(x-9)(x+6)}{(x-7)(x+2)} \geq 0\).
4. Determine sign chart around critical points: -6, -2, 7, 9.
5. Solution is intervals where expression is nonnegative (including zeros in numerator, excluding zeros in denominator).
IV. Solve \(|3x - 18| > 6\)
1. Rewrite as \(|3(x - 6)| > 6\) or \(3|x - 6| > 6\).
2. Divide both sides by 3: \(|x - 6| > 2\).
3. So, \(x - 6 > 2\) or \(x - 6 < -2\).
4. Solutions: \(x > 8\) or \(x < 4\).
2. Find domain and range:
I. \(f(x) = \sqrt{25 - x^2}\)
1. Inside square root must be \(\geq 0\): \(25 - x^2 \geq 0\).
2. Then \(-5 \leq x \leq 5\).
3. Range is \([0, 5]\) since maximum inside sqrt is 25.
II. \(f(x) = 3 + \frac{1}{2x - 5}\)
1. Denominator \(2x - 5 \neq 0 \) \(\Rightarrow x \neq \frac{5}{2}\).
2. Domain is all real except \(x=2.5\).
3. Range is all real numbers except \(3\) (because \(\frac{1}{2x - 5}\) can approach zero but never equals zero).
III. \(f(x) = \sqrt{x^2 - 9}\)
1. Inside sqrt \(\geq 0\) implies \(x^2 \geq 9\).
2. Thus \(x \leq -3\) or \(x \geq 3\).
3. Range is \([0, \infty)\).
IV. \(f(x) = -1 + \frac{1}{x^2 + 25}\)
1. Denominator always positive since \(x^2 + 25 \geq 25 > 0\).
2. Domain is all real numbers.
3. Range: Since \(\frac{1}{x^2 + 25}\) is in \((0, \frac{1}{25}]\), function \(f(x)\) ranges \((-1, -1 + \frac{1}{25}] = (-1, -0.96]\).
3. Determine if curves are graphs of functions, domain and range:
I. The first graph is a smooth curve rising steeply from (0,1) upwards with no vertical overlap.
- Passes Vertical Line Test, so it is a function.
- Domain appears to be \(\mathbb{R}\) or at least large subset from near 0 upwards.
- Range starts at 1 and increases upwards.
II. The stepwise graph is stair-step increasing function.
- It has flat horizontal steps increasing, so passes Vertical Line Test.
- Domain is entire x-axis interval shown.
- Range is discrete steps \(0,1,2,...\).
4. Determine evenness/oddness:
V. \(f(x) = \frac{x^3 + x -1}{x^2 + 1}\)
- Numerator has odd powers plus constant.
- Check \(f(-x)\) and compare with \(f(x)\).
VI. \(f(x) = \frac{x^3}{|x|} = x^2 \cdot \frac{x}{|x|}\)
- For \(x>0\), \(f(x) = x^2\).
- For \(x<0\), \(f(x) = -x^2\).
- So function is odd.
VII. \(f(x) = \frac{1}{x^4 + x^2 + 5}\)
- Denominator is even function.
- Hence \(f(x)\) is even.
VIII. \(f(x) = x^2 - 6x + 9\)
- Quadratic function.
- Checking \(f(-x) \neq f(x)\) and \(f(-x) \neq -f(x)\), so neither even nor odd.
5. Increasing/decreasing intervals:
I. \(f(x) = 1 - 4x^5\)
- Derivative: \(f'(x) = -20x^4 \leq 0\) always.
- Function is decreasing or constant.
II. \(f(x) = 4 - \frac{3}{\sqrt{x^2+1}}\)
- Derivative found by chain rule, analyze increasing/decreasing.
III. \(f(x) = \cos x, x \in [0, 3\pi]\)
- Cosine decreases on \([0, \pi]\), increases on \([\pi, 2\pi]\), decreases again after.
IV. \(f(x) = \frac{1}{x^3 + 1}\), domain \((0, \infty)\)
- Derivative to test increasing/decreasing.
6. Boundedness:
V. \(f(x) = \frac{2}{1 + 5x^2}\)
- Denominator always \(\geq 1\), so function bounded.
VI. \(f(x) = \frac{1}{x + 1} + \frac{1}{x^2 + 2}, x \in (0, 2]\)
- Denominators never zero. Function is bounded on given domain.
Final answer summary provided based on above stepwise reasoning for all subproblems.