Math  /  Algebra

Question(b) By writing xa|x| \geq a in the equivalent for xax \geq a or xax \leq-a, determine the solution set for x32x112\left|\frac{x-3}{2 x-1}\right| \geq \frac{1}{2} [6 marks]

Studdy Solution

STEP 1

1. The inequality involves an absolute value, which can be split into two separate inequalities.
2. The expression inside the absolute value is a rational function.
3. The inequality xa |x| \geq a is equivalent to xa x \geq a or xa x \leq -a .

STEP 2

1. Rewrite the inequality without the absolute value.
2. Solve the inequality x32x112 \frac{x-3}{2x-1} \geq \frac{1}{2} .
3. Solve the inequality x32x112 \frac{x-3}{2x-1} \leq -\frac{1}{2} .
4. Combine the solution sets from steps 2 and 3.
5. Consider any restrictions on the domain of the function.

STEP 3

Rewrite the inequality x32x112 \left|\frac{x-3}{2x-1}\right| \geq \frac{1}{2} as two separate inequalities:
x32x112orx32x112 \frac{x-3}{2x-1} \geq \frac{1}{2} \quad \text{or} \quad \frac{x-3}{2x-1} \leq -\frac{1}{2}

STEP 4

Solve the inequality x32x112 \frac{x-3}{2x-1} \geq \frac{1}{2} :
First, cross-multiply to eliminate the fraction, being mindful of the sign of 2x1 2x-1 :
2(x3)(2x1) 2(x-3) \geq (2x-1)
Simplify and solve for x x :
2x62x1 2x - 6 \geq 2x - 1
Subtract 2x 2x from both sides:
61 -6 \geq -1
This inequality is always false, so there is no solution from this inequality.

STEP 5

Solve the inequality x32x112 \frac{x-3}{2x-1} \leq -\frac{1}{2} :
Cross-multiply to eliminate the fraction:
2(x3)(2x1) 2(x-3) \leq -(2x-1)
Simplify and solve for x x :
2x62x+1 2x - 6 \leq -2x + 1
Add 2x 2x to both sides:
4x61 4x - 6 \leq 1
Add 6 to both sides:
4x7 4x \leq 7
Divide by 4:
x74 x \leq \frac{7}{4}

STEP 6

Combine the solution sets from steps 2 and 3:
Since the first inequality had no solution, the solution set is determined solely by the second inequality:
x74 x \leq \frac{7}{4}

STEP 7

Consider any restrictions on the domain of the function:
The expression x32x1 \frac{x-3}{2x-1} is undefined when the denominator is zero, i.e., 2x1=0 2x - 1 = 0 , which gives x=12 x = \frac{1}{2} .
Therefore, the solution set must exclude x=12 x = \frac{1}{2} .
The final solution set is:
x74,x12 x \leq \frac{7}{4}, \, x \neq \frac{1}{2}
The solution set is:
x74,x12 \boxed{x \leq \frac{7}{4}, \, x \neq \frac{1}{2}}

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