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QJEEM21Ma0ccd: JEE Main 2021 Mathematics - Class 12 JEEM21Ma0ccd Solution: Let [t] denote the greatest integer t. Then the value of is…

Let [t] denote the greatest integer ≤\le t. Then the value of

8.∫−121([2x]+∣x∣)dx8.\int\limits_{ - {1 \over 2}}^1 {([2x] + |x|)dx} is ___________.

Step-by-Step Verified Solution

I= ∫−121([2x]+∣x∣)dxI = \,\int\limits_{ - {1 \over 2}}^1 {([2x] + |x|)dx}

=∫−1/21[2x] dx+∫−1/21∣x∣ dx= \int\limits_{ - 1/2}^1 {[2x]\,dx + \int\limits_{ - 1/2}^1 {|x|\,} dx}

=0+∫−1/20(−x) dx+∫01x dx= 0 + \int\limits_{ - 1/2}^0 {( - x)\,} dx + \int\limits_0^1 {x\,} dx

=(−x22)−1/20+(x22)01= \left( { - {{{x^2}} \over 2}} \right)_{ - 1/2}^0 + \left( {{{{x^2}} \over 2}} \right)_0^1

=(0+18)+12= \left( {0 + {1 \over 8}} \right) + {1 \over 2}

=58= {5 \over 8}

∴\therefore 8I = 5

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