Various Algebra Problems
1. Solve the equation $3|2t-1|-4=16$ for $t$.
Start by isolating the absolute value:
$$3|2t-1|=20$$
Divide both sides by 3:
$$|2t-1|=\frac{20}{3}$$
This gives two cases:
Case 1: $2t-1=\frac{20}{3}$
$$2t=\frac{20}{3}+1=\frac{23}{3} \Rightarrow t=\frac{23}{6}$$
Case 2: $2t-1=-\frac{20}{3}$
$$2t=-\frac{20}{3}+1=-\frac{17}{3} \Rightarrow t=-\frac{17}{6}$$
2. Solve the inequality
$$\frac{x-3}{x-2} < \frac{x+1}{x+4}, x \neq 2, x \neq -4$$
Bring terms to one side:
$$\frac{x-3}{x-2} - \frac{x+1}{x+4} < 0$$
Find common denominator $(x-2)(x+4)$:
$$\frac{(x-3)(x+4)-(x+1)(x-2)}{(x-2)(x+4)} < 0$$
Expand:
$$(x^2 +4x -3x -12) - (x^2 -2x + x -2) = (x^2 + x -12) - (x^2 - x -2) = x^2 + x -12 - x^2 + x + 2 = 2x -10$$
So inequality:
$$\frac{2x -10}{(x-2)(x+4)} < 0$$
Factor numerator:
$$\frac{2(x-5)}{(x-2)(x+4)} < 0$$
Find intervals considering critical points $-4, 2, 5$, test signs:
Solution intervals where fraction is negative:
$$(-\infty,-4) \cup (2,5)$$
3. Graph of $f(x) = 4x^2 -1$ and line $y=3x+2$
Set equal to find intersection:
$$4x^2 -1 = 3x + 2$$
$$4x^2 - 3x -3 = 0$$
Use quadratic formula:
$$x = \frac{3 \pm \sqrt{9 + 48}}{8} = \frac{3 \pm \sqrt{57}}{8}$$
These are the intersection points.
4. Solve compound inequality:
$$-2 > x^2 + x > 6$$
No real $x$ satisfies since $x^2 + x$ cannot be simultaneously less than $-2$ and greater than $6$.
5. For
$$1 < x + \frac{6}{x} > 5$$
Rewrite as two inequalities:
$$1 < x + \frac{6}{x} \quad \text{and} \quad x + \frac{6}{x} > 5$$
But this is contradictory; likely question needs clarification.
6. Inequality:
$$\frac{x+1}{x-2} \leq \frac{x}{x+3}$$
Bring terms to one side:
$$\frac{x+1}{x-2} - \frac{x}{x+3} \leq 0$$
Common denominator $(x-2)(x+3)$:
$$\frac{(x+1)(x+3) - x(x-2)}{(x-2)(x+3)} \leq 0$$
Expand numerator:
$$(x^2 +3x + x +3) - (x^2 -2x) = (x^2 +4x +3) - (x^2 -2x) = 6x + 3$$
Inequality:
$$\frac{6x + 3}{(x-2)(x+3)} \leq 0$$
Critical points at $x=-\frac{1}{2}, 2, -3$, test intervals to find solution.
7. For $f(x) = x^2 + 4x$, domain $0 > x > 4$ is likely typo; assume domain $0 \leq x \leq 4$.
Compute range:
$$f(x) = x^2 +4x = (x+2)^2 -4$$
Minimum at $x=-2$ not in domain.
Check endpoints:
$$f(0) = 0$$
$$f(4) = 16 +16 = 32$$
Since function is increasing in $[0,4]$, range is $[0,32]$.
8. For $g(x)= x^2 -4x$, domain $-2 > x \geq 3$ likely typo; if domain $-2 \leq x \leq 3$.
Plot the function accordingly.
9. Given:
$$(2x+3)(x-5) = 0$$
a) Expand:
$$2x^2 -10x +3x -15 = 2x^2 -7x -15 = 0$$
b) Vertex:
$$x = -\frac{b}{2a} = -\frac{-7}{4} = \frac{7}{4} = 1.75$$
$$y = 2(1.75)^2 -7(1.75) -15 = 2(3.0625) - 12.25 -15 = 6.125 -27.25 = -21.125$$
c) Plot the parabola.
10. For $f(x) = 4x - x^2$
(a) Domain: $x \in \mathbb{R}$
(b) Range: Vertex at $x=2$,
$$f(2) = 4(2) - 4 = 8 -4 = 4$$
Parabola opens downward, so range $(-\infty, 4]$
11. For $f(x) = x^2 + 2x + 5$, domain $-1 \leq x < 3$
Complete the square:
$$f(x) = (x+1)^2 +4$$
Minimum at $x = -1$, $f(-1)=4$
Maximum at $x \to 3$, value near $f(3)=9 +6 +5=20$
Range $[4, 20)$.
12. Compose functions:
$f(x)= 2x - x^2$, $g(x)=1 - x^{-2}$
Calculate $f^{-1} \circ g$ and $f \circ g$ accordingly.
13. For $f(x)= x+2$, $g(x) = x^2 + 2x + 3$
a) $(g \circ f)(x) = g(f(x)) = (x+2)^2 + 2(x+2) +3 = x^2 + 4x +4 + 2x +4 +3 = x^2 + 6x + 11$
b) Evaluate at $x = -\frac{1}{4}$:
$(-\frac{1}{4})^2 + 6(-\frac{1}{4}) +11 = \frac{1}{16} - \frac{3}{2} +11 = \frac{1}{16} - \frac{24}{16} + \frac{176}{16} = \frac{153}{16} = 9.5625$
14. For perpendicular lines $y = 3x - 6$ and $y = mx + 7$:
Slope product $3 \cdot m = -1$, so
$$m = -\frac{1}{3}$$
Plot both lines.
15. Slope between $A(3,4)$ and $B(6,1)$:
$$m = \frac{1 -4}{6 -3} = \frac{-3}{3} = -1$$
Equation:
$$y - 4 = -1(x - 3) \Rightarrow y = -x + 7$$
Plot line.
16. For $g(x) = x - \frac{1}{x}$, $x \neq 0$, $f(x) = x + 3$, $h(x) = 2x - 4$
Find inverses and compositions as requested.
Final answers are provided through explanations and detailed intermediate steps.