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    Question

    Which of the following is not a quadratic

    equation?
    A K(3K−7) = (K+2)² Correct Answer Incorrect Answer
    B (2K−3)(K+1) = (K−3)(2K+6) Correct Answer Incorrect Answer
    C (K+2)²+5 = 5K−17 Correct Answer Incorrect Answer
    D (K−7)²+5K = 3K²−8 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Option 1: LHS = K(3K−7) = 3K²−7K RHS = (K+2)² = K²+4K+4 → Quadratic ✅ Option 2: LHS = (2K−3)(K+1) = 2K²−K−3 RHS = (K−3)(2K+6) = 2K²−18 Equation: 2K²−K−3 = 2K²−18 Cancel 2K² → −K−3 = −18 → K = 15 → Linear ❌ → Not quadratic Option 3: LHS = (K+2)² + 5 = K²+4K+9 RHS = 5K−17 → Quadratic ✅ Option 4: LHS = (K−7)² + 5K = K²−14K+49 + 5K = K²−9K+49 RHS = 3K²−8 → Quadratic ✅ Hence, Option 2 is NOT a quadratic equation ✅

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