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∫25∣x−3∣dx\int_2^5 |x - 3|dx equals

Solution

✅ Correct Option: 2

The absolute value ∣x−3∣|x - 3| represents the distance between xx and 33. To integrate, the absolute value must be removed:

  • When x≥3x \geq 3: ∣x−3∣=x−3|x - 3| = x - 3
  • When x<3x < 3: ∣x−3∣=−(x−3)=3−x|x - 3| = -(x - 3) = 3 - x

Since the integration is from 22 to 55 and the expression changes at x=3x = 3, split the integral at x=3x = 3:

∫25∣x−3∣dx=∫23∣x−3∣dx+∫35∣x−3∣dx\int_2^5 |x - 3|dx = \int_2^3 |x - 3|dx + \int_3^5 |x - 3|dx


For x∈[2,3]x \in [2, 3]: ∣x−3∣=3−x|x - 3| = 3 - x

For x∈[3,5]x \in [3, 5]: ∣x−3∣=x−3|x - 3| = x - 3

∫25∣x−3∣dx=∫23(3−x)dx+∫35(x−3)dx\int_2^5 |x - 3|dx = \int_2^3 (3-x)dx + \int_3^5 (x-3)dx


∫23(3−x)dx=[3x−x22]23\int_2^3 (3-x)dx = \left[3x - \frac{x^2}{2}\right]_2^3

At x=3x = 3: 3(3)−322=9−92=923(3) - \frac{3^2}{2} = 9 - \frac{9}{2} = \frac{9}{2}

At x=2x = 2: 3(2)−222=6−2=43(2) - \frac{2^2}{2} = 6 - 2 = 4

∫23(3−x)dx=92−4=12\int_2^3 (3-x)dx = \frac{9}{2} - 4 = \frac{1}{2}


∫35(x−3)dx=[x22−3x]35\int_3^5 (x-3)dx = \left[\frac{x^2}{2} - 3x\right]_3^5

At x=5x = 5: 522−3(5)=252−15=−52\frac{5^2}{2} - 3(5) = \frac{25}{2} - 15 = -\frac{5}{2}

At x=3x = 3: 322−3(3)=92−9=−92\frac{3^2}{2} - 3(3) = \frac{9}{2} - 9 = -\frac{9}{2}

∫35(x−3)dx=−52−(−92)=2\int_3^5 (x-3)dx = -\frac{5}{2} - \left(-\frac{9}{2}\right) = 2


∫25∣x−3∣dx=12+2\int_2^5 |x - 3|dx = \frac{1}{2} + 2

=12+42= \frac{1}{2} + \frac{4}{2}

=52= \frac{5}{2}

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