Additional Mathematics – Equations, inequalities and graphs | e-Consult
Equations, inequalities and graphs (1 questions)
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First require the right‑hand side to be non‑negative:
2x − 1 ≥ 0 ⟹ x ≥ ½
Now remove the modulus by writing two simultaneous inequalities:
- |x² − 4x + 3| ≤ 2x − 1 ⟹
- x² − 4x + 3 ≤ 2x − 1 ⟹ x² − 6x + 4 ≤ 0
- x² − 4x + 3 ≥ −(2x − 1) ⟹ x² − 2x + 2 ≥ 0
Second inequality x² − 2x + 2 ≥ 0 holds for all real x (discriminant
Solve the first quadratic inequality:
Δ = (−6)² − 4·1·4 = 20, √Δ = 2√5
Roots: x = [6 ± 2√5]/2 = 3 ± √5
Since the coefficient of x² is positive, the expression ≤ 0 between the roots:
3 − √5 ≤ x ≤ 3 + √5
Combine with the domain x ≥ ½. Because 3 − √5 ≈ 0.764 > ½, the domain condition is already satisfied.
Therefore the solution set is
| [3 − √5, 3 + √5] |