JEE MAIN - Mathematics (2025 - 3rd April Morning Shift - No. 8)
Explanation
Step 1: Ensure the innermost function is greater than zero:
$ \log_6(3 + 4x - x^2) > 1 $
Step 2: Simplify the inequality from Step 1:
$ 3 + 4x - x^2 > 6 \implies x^2 - 4x + 3 < 0 $
Step 3: Solve the quadratic inequality:
$ (x - 1)(x - 3) < 0 $
This inequality indicates that $ x $ must lie between the roots, giving the interval $ x \in (1, 3) $.
With the domain of $ f(x) $ identified as $ (a, b) = (1, 3) $, we calculate the definite integral over $[0, b-a]$:
Calculate the Integral:
Given:
$ \int_0^{b-a} [x^2] \, dx $
For $ b - a = 2 $, we compute:
$ \int_1^2 [x^2] \, dx = \int_1^{\sqrt{2}} 1 \, dx + \int_{\sqrt{2}}^{\sqrt{3}} 2 \, dx + \int_{\sqrt{3}}^2 3 \, dx $
Computation of Each Integral Segment:
$\int_1^{\sqrt{2}} 1 \, dx = \sqrt{2} - 1$
$\int_{\sqrt{2}}^{\sqrt{3}} 2 \, dx = 2(\sqrt{3} - \sqrt{2})$
$\int_{\sqrt{3}}^2 3 \, dx = 3(2 - \sqrt{3})$
Summing these, we have:
$ 5 - \sqrt{2} - \sqrt{3} $
Conclusion:
The values for $ p, q, $ and $ r $ are $ p = 5 $, $ q = 2 $, and $ r = 3 $, with the greatest common divisor of these numbers being 1. Therefore, adding them together gives:
$ p + q + r = 5 + 2 + 3 = 10 $
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