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If [x] represents the greatest integer not exceeding x, then \(\rm \int_0^9 [x]\ dx\) is1. 322. 363. 404. 28 |
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Answer» Correct Answer - Option 2 : 36 Concept: Definite Integral: If ∫ f(x) dx = g(x) + C, then \(\rm\int_a^b f(x)\ dx= [ g(x)]_a^b\) = g(b) - g(a).
Calculation: [x] is a multi-valued function in the interval 0-9, with: [x] = 0, x ∈ (0, 1) [x] = 1, x ∈ (1, 2) [x] = 2, x ∈ (2, 3) And so on. ∴ \(\rm \int_0^9 [x]\ dx\) = \(\rm \int_0^1 0\ dx+\int_1^2 1\ dx\ +\ ...\ +\int_8^9 8\ dx\) = \(0[x]_0^1+1[x]_1^2\ +\ ...\ +8[x]_8^9\) = 0[1 - 0] + 1[2 - 1] + ... + 8[9 - 8] = 0 + 1 + 2 + ... + 8 = \(\frac{8(8+1)}{2}\) = 36. |
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