What is the solution set to the inequality [tex](4x-3)(2x-1) \geq 0[/tex]?

A. [tex]\{x \mid x \leq 3 \text{ or } x \geq 1\}[/tex]

B. [tex]\left\{x \mid x \leq 2 \text{ or } x \geq \frac{4}{3}\right\}[/tex]

C. [tex]\left\{x \mid x \leq \frac{1}{2} \text{ or } x \geq \frac{3}{4}\right\}[/tex]

D. [tex]\left\{x \mid x \leq -\frac{1}{2} \text{ or } x \geq -\frac{3}{4}\right\}[/tex]



Answer :

To solve the inequality [tex]\((4x - 3)(2x - 1) \geq 0\)[/tex], you can follow these steps:

1. Identify the critical points:
The critical points occur when each factor equals zero. That is:
[tex]\[ 4x - 3 = 0 \quad \text{and} \quad 2x - 1 = 0. \][/tex]
Solving these equations, we get:
[tex]\[ x = \frac{3}{4} \quad \text{and} \quad x = \frac{1}{2}. \][/tex]

2. Determine the intervals defined by the critical points:
The critical points divide the number line into three intervals:
[tex]\[ (-\infty, \frac{1}{2}), \quad (\frac{1}{2}, \frac{3}{4}), \quad \text{and} \quad (\frac{3}{4}, \infty). \][/tex]

3. Test a point from each interval to determine the sign of the expression in that interval:
- For [tex]\( x < \frac{1}{2} \)[/tex], choose [tex]\( x = 0 \)[/tex]:
[tex]\[ (4 \cdot 0 - 3)(2 \cdot 0 - 1) = (-3)(-1) = 3 \geq 0. \][/tex]
- For [tex]\( \frac{1}{2} < x < \frac{3}{4} \)[/tex], choose [tex]\( x = \frac{2}{3} \)[/tex]:
[tex]\[ \left( 4 \cdot \frac{2}{3} - 3 \right)\left( 2 \cdot \frac{2}{3} - 1 \right) = \left( \frac{8}{3} - 3 \right)\left( \frac{4}{3} - 1 \right) = \left( \frac{8}{3} - \frac{9}{3} \right)\left( \frac{4}{3} - \frac{3}{3} \right) = \left( -\frac{1}{3} \right)\left( \frac{1}{3} \right) = -\frac{1}{9} < 0. \][/tex]
- For [tex]\( x > \frac{3}{4} \)[/tex], choose [tex]\( x = 1 \)[/tex]:
[tex]\[ (4 \cdot 1 - 3)(2 \cdot 1 - 1) = (4 - 3)(2 - 1) = 1 \geq 0. \][/tex]

4. Combine the intervals where the expression is non-negative:
- From the tests above, the intervals that satisfy the inequality [tex]\((4x - 3)(2x - 1) \geq 0\)[/tex] are:
[tex]\[ (-\infty, \frac{1}{2}] \quad \text{and} \quad [\frac{3}{4}, \infty). \][/tex]

Thus, the solution set to the inequality [tex]\((4x-3)(2x-1) \geq 0\)[/tex] is:
[tex]\[ \left\{ x \left| x \leq \frac{1}{2} \right. \text{ or } x \geq \frac{3}{4} \right\}. \][/tex]

Therefore, the correct answer is:
[tex]\[ \left\{ x \left| x \leq \frac{1}{2} \right. \text{ or } x \geq \frac{3}{4} \right\}. \][/tex]