The number of solutions of the equation left(frac9x -frac9sqrtx +2right)left(frac2x -frac7sqrtx +3right) = 0 is:

Solution & Explanation

### Related Formula textSubstitute variable to convert non-linear form: alpha = frac1sqrtx quad (x > 0) ### Core Logic Let frac1sqrtx = alpha. The equation reduces to a product of two quadratics: (9alpha^2 - 9alpha + 2)(2alpha^2 - 7alpha + 3) = 0 ### Step 1: Factorize the components First quadratic: 9alpha^2 - 9alpha + 2 = 0 implies (3alpha - 2)(3alpha - 1) = 0 implies alpha = frac23, frac13 Second quadratic: 2alpha^2 - 7alpha + 3 = 0 implies (2alpha - 1)(alpha - 3) = 0 implies alpha = frac12, 3 ### Step 2: Solve for x Since alpha = frac1sqrtx implies x = frac1alpha^2. For alpha = frac13 implies x = 9 For alpha = frac12 implies x = 4 For alpha = frac23 implies x = frac94 For alpha = 3 implies x = frac19 All 4 values are positive and valid. ### Pattern Recognition Always check constraints first (x > 0 due to sqrtx in denominator). Since all roots alpha > 0, every single algebraic root maps to a real distinct solution. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Quadratic Equations

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Q20 jee_main_2024_31_jan_morning Sign of Quadratic Expressions
Let S be the set of positive integral values of a for which fracax^2 + 2(a + 1)x + 9a + 4x^2 - 8x + 32 < 0, forall x in mathbbR. Then, the number of elements in S is:
  • A. 1
  • B. 0
  • C. infty
  • D. 3

Solution

### Core Logic For the denominator x^2 - 8x + 32, D = 64 - 128 < 0 and a = 1 > 0. Thus, x^2 - 8x + 32 > 0 forall x in mathbbR. ### Step 1: Constraint on Numerator Since the denominator is always positive, the numerator must be strictly negative for all x in mathbbR. ax^2 + 2(a + 1)x + 9a + 4 < 0 quad forall x in mathbbR This requires a < 0 and D < 0. ### Step 2: Conclusion Since a must be strictly less than 0, there are no *positive* integral values of a that satisfy the condition. Hence, S is an empty set. Number of elements is 0. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Quadratic Equations

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