tìm x ----- Nội dung ảnh ----- 4. \((x-2)^2 - (x+1)(x-3) = -7\) 5. \((x+1)^2 - (2x+2)(x-2) = 0\) 6. \((2x+3)^2 - 4(x-1)^2 = 16\) 7. \(27x^2(x+1) - (3x+1)^2 = -8\) 8. \((2x+3)^2 - 4(x+1)^2 = 0\)
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62 Tham khảo câu trả lời từ Trợ lý ảo Lazi To find \( x \) in each equation, let's solve them step by step. **Equation 4:** \[ (x - 2)^2 - [(2x+1)(x-3)] = -7 \] Expand and simplify: 1. \( (x - 2)^2 = x^2 - 4x + 4 \) 2. \( (2x+1)(x-3) = 2x^2 - 6x + x - 3 = 2x^2 - 5x - 3 \) Substitute into the equation: \[ x^2 - 4x + 4 - (2x^2 - 5x - 3) = -7 \] Simplify: \[ x^2 - 4x + 4 - 2x^2 + 5x + 3 = -7 \] \[ -x^2 + x + 7 = -7 \] Rearrange: \[ -x^2 + x + 14 = 0 \] Multiply all terms by -1: \[ x^2 - x - 14 = 0 \] Solve this quadratic equation using the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) with \( a = 1, b = -1, c = -14 \). \[ b^2 - 4ac = 1 + 56 = 57 \] Solution: \( x = \frac{1 \pm \sqrt{57}}{2} \). --- **Equation 5:** \[ (x + 1)^2 - (2x + 2)(x - 2) = 0 \] Expand and simplify: 1. \( (x + 1)^2 = x^2 + 2x + 1 \) 2. \( (2x+2)(x-2) = 2x^2 - 4x + 2x - 4 = 2x^2 - 2x - 4 \) Substitute into the equation: \[ x^2 + 2x + 1 - (2x^2 - 2x - 4) = 0 \] Simplify: \[ x^2 + 2x + 1 - 2x^2 + 2x + 4 = 0 \] \[ -x^2 + 4x + 5 = 0 \] Change signs: \[ x^2 - 4x - 5 = 0 \] Factor: \[ (x - 5)(x + 1) = 0 \] Solution: \( x = 5 \) or \( x = -1 \). --- **Equation 6:** \[ (2x + 3)^2 - 4(x - 1)^2 = 18 \] Expand and simplify: 1. \( (2x + 3)^2 = 4x^2 + 12x + 9 \) 2. \( 4(x - 1)^2 = 4(x^2 - 2x + 1) = 4x^2 - 8x + 4 \) Substitute into the equation: \[ 4x^2 + 12x + 9 - (4x^2 - 8x + 4) = 18 \] Simplify: \[ 4x^2 + 12x + 9 - 4x^2 + 8x - 4 = 18 \] \[ 20x + 5 = 18 \] Rearrange: \[ 20x = 13 \] Solution: \( x = \frac{13}{20} \). --- **Equation 7:** \[ 27x^2(x + 1) - (3x + 1)^2 = -8 \] Expand: 1. \( 27x^2(x + 1) = 27x^3 + 27x^2 \) 2. \( (3x + 1)^2 = 9x^2 + 6x + 1 \) Substitute into the equation: \[ 27x^3 + 27x^2 - (9x^2 + 6x + 1) = -8 \] Simplify: \[ 27x^3 + 27x^2 - 9x^2 - 6x - 1 = -8 \] \[ 27x^3 + 18x^2 - 6x - 1 = -8 \] Rearrange: \[ 27x^3 + 18x^2 - 6x + 7 = 0 \] Solution (find numerically or factor if possible). --- **Equation 8:** \[ (3x + 3)^2 - 4(x - 1)^2 = 0 \] Expand: 1. \( (3x + 3)^2 = 9x^2 + 18x + 9 \) 2. \( 4(x - 1)^2 = 4(x^2 - 2x + 1) = 4x^2 - 8x + 4 \) Substitute into the equation: \[ 9x^2 + 18x + 9 - (4x^2 - 8x + 4) = 0 \] Simplify: \[ 9x^2 + 18x + 9 - 4x^2 + 8x - 4 = 0 \] \[ 5x^2 + 26x + 5 = 0 \] Solve using the quadratic formula with \( a = 5, b = 26, c = 5 \). Discriminant: \( b^2 - 4ac = 676 - 100 = 576 \) Solution: \( x = \frac{-26 \pm 24}{10} \), which gives \( x_1 = -\frac{1}{5} \), and \( x_2 = -5 \).