WBBSEClass XMathematicsQuadratic Surds01 Mark2025 Easy

QQuestion

If the sum of the square of the roots of the equation 6x² + x + k = 0 is 25\over36, then the value of k is 12.

Exam-ready answer 01 Mark

Answer

False

Explanation:

The sum of the squares of the roots of a quadratic equation ax^2 + bx + c = 0 is given by:

α2 + β2 = (α + β)– 2αβ

From the given equation 6x² + x + k = 0,

Sum of roots: α + β = -\frac{b}{a} = -\frac{1}{6}

Product of roots: α × β = \frac{c}{a} = \frac{k}{6}

Using the formula:

\left(-\frac{1}{6} \right)^2 - 2 \times \frac{k}{6} = \frac{25}{36}

Solving, k \neq 12

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