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QJEEM22Ma24f8: JEE Main 2022 Mathematics - Class 12 JEEM22Ma24f8 Solution: Let . Consider Then,

Let f(x)=2+∣x∣−∣x−1∣+∣x+1∣,x∈Rf(x)=2+|x|-|x-1|+|x+1|, x \in \mathbf{R} .

Consider

(S1):f′(−32)+f′(−12)+f′(12)+f′(32)=2(\mathrm{S} 1): f^{\prime}\left(-\frac{3}{2}\right)+f^{\prime}\left(-\frac{1}{2}\right)+f^{\prime}\left(\frac{1}{2}\right)+f^{\prime}\left(\frac{3}{2}\right)=2

(S2):∫−22f(x)dx=12(\mathrm{S} 2): \int\limits_{-2}^{2} f(x) \mathrm{d} x=12

Then,

Multiple Choice Options

  • A both (S1) and (S2) are correct
  • B both (S1) and (S2) are wrong
  • C only (S1) is correct
  • D only (S2) is correct

Step-by-Step Verified Solution

f(x)=2+∣x∣−∣x−1∣+∣x+1∣, x∈Rf(x) = 2 + |x| - |x - 1| + |x + 1|,\,x \in R

∴\therefore f(x)={−x,x<−1x+2,−1≤x<03x+2,0≤x<1x+4,x≥1

∴\therefore f′(−32)+f′(−12)+f′(12)+f′(32)=−1+1+3+1=4f'\left( { - {3 \over 2}} \right) + f'\left( { - {1 \over 2}} \right) + f'\left( {{1 \over 2}} \right) + f'\left( {{3 \over 2}} \right) = - 1 + 1 + 3 + 1 = 4

and ∫−22f(x)dx=∫−2−1f(x)dx+∫−10f(x)dx+∫01f(x)dx+∫12f(x)dx\int\limits_{ - 2}^2 {f(x)dx = \int\limits_{ - 2}^{ - 1} {f(x)dx + \int\limits_{ - 1}^0 {f(x)dx + \int\limits_0^1 {f(x)dx + \int\limits_1^2 {f(x)dx} } } } }

=[−x22]2−1+[(x+2)22]−10+[(3x+2)26]01+[(x+4)22]12= \left[ { - {{{x^2}} \over 2}} \right]_2^{ - 1} + \left[ {{{{{(x + 2)}^2}} \over 2}} \right]_{ - 1}^0 + \left[ {{{{{(3x + 2)}^2}} \over 6}} \right]_0^1 + \left[ {{{{{(x + 4)}^2}} \over 2}} \right]_1^2

=32+32+72+112=242=12= {3 \over 2} + {3 \over 2} + {7 \over 2} + {{11} \over 2} = {{24} \over 2} = 12

∴\therefore Only (S2) is correct

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