### **1.** $(2x - 1)^2 - (4x^2 - 1) = 0$
Khai triển:
$(4x^2 - 4x + 1) - (4x^2 - 1) = 0$
➡ $4x^2 - 4x + 1 - 4x^2 + 1 = 0$
➡ $-4x + 2 = 0$
➡ $x = \dfrac{1}{2}$
**Đáp án:** $x = \dfrac{1}{2}$
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### **2.** $(x + 2)^2 - x(x - 3) = 2$
Khai triển:
$(x^2 + 4x + 4) - (x^2 - 3x) = 2$
➡ $x^2 + 4x + 4 - x^2 + 3x = 2$
➡ $7x + 4 = 2$
➡ $7x = -2$
➡ $x = -\dfrac{2}{7}$
**Đáp án:** $x = -\dfrac{2}{7}$
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### **3.** $(x - 5)^2 - x(x + 2) = 5$
Khai triển:
$(x^2 - 10x + 25) - (x^2 + 2x) = 5$
➡ $x^2 - 10x + 25 - x^2 - 2x = 5$
➡ $-12x + 25 = 5$
➡ $-12x = -20$
➡ $x = \dfrac{5}{3}$
**Đáp án:** $x = \dfrac{5}{3}$
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### **4.** $(x - 1)^2 + x(4 - x) = 11$
Khai triển:
$x^2 - 2x + 1 + 4x - x^2 = 11$
➡ $-2x + 1 + 4x = 11$
➡ $2x + 1 = 11$
➡ $2x = 10$
➡ $x = 5$
**Đáp án:** $x = 5$
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### **5.** $(x - 3)(x + 3) = (x - 5)^2$
Trái: $x^2 - 9$
Phải: $x^2 - 10x + 25$
➡ $x^2 - 9 = x^2 - 10x + 25$
➡ Trừ 2 vế: $-9 = -10x + 25$
➡ $-10x = -34$
➡ $x = \dfrac{17}{5}$
**Đáp án:** $x = \dfrac{17}{5}$