Analyzing the Setup
We are tasked with evaluating the integral:
12∫03∣x2−3x+2∣dx
The modulus function acts as a filter that ensures the output is always non-negative. To evaluate this, we must analyze the behavior of the quadratic function f(x)=x2−3x+2.
By factorizing the quadratic, we find:
x2−3x+2=(x−1)(x−2)
The roots of the function are x=1 and x=2. These points are critical because they define where the parabola crosses the x-axis and where the sign of the expression changes.
The Modulus Trap
As we traverse the interval [0,3], the function f(x) behaves differently in three distinct regions:
1. On [0,1], f(x)≥0.
2. On [1,2], f(x)<0.
3. On [2,3], f(x)≥0.
Because of the modulus, we must negate the expression in the interval where it is negative to ensure the area remains positive. We split the integral accordingly:
12[∫01(x2−3x+2)dx−∫12(x2−3x+2)dx+∫23(x2−3x+2)dx]
The Calculation
The antiderivative of
f(x)=x2−3x+2 is given by:
F(x)=3x3−23x2+2x
We evaluate F(x) at the boundaries 0,1,2, and 3:
F(0)=0
F(1)=31−23+2=65
F(2)=38−6+4=32
F(3)=9−227+6=23
Now, we compute the value of each segment:
First part: F(1)−F(0)=65
Second part: −(F(2)−F(1))=−(32−65)=−(−61)=61
* Third part: F(3)−F(2)=23−32=65
Final Result
Summing these components, we obtain:
65+61+65=611
Finally, multiplying by the constant
12 outside the integral:
12×611=22
The final answer is 22.