- Given functions
We have
f(x)={−2,x−2,−2≤x≤00<x≤2
and
h(x)=f(∣x∣)+∣f(x)∣.
We need to evaluate
∫−22h(x)dx.
- Find f(∣x∣)
Since ∣x∣∈[0,2] for x∈[−2,2]:
- if x=0, then f(∣x∣)=f(0)=−2,
- if x=0, then ∣x∣>0, so we use the second branch:
f(∣x∣)=∣x∣−2.
Thus, for integration purposes,
f(∣x∣)=∣x∣−2(except at x=0, where it is −2).
A single point does not affect the integral.
- Find ∣f(x)∣ piecewise
-
For −2≤x≤0:
f(x)=−2⟹∣f(x)∣=2.
-
For 0<x≤2:
f(x)=x−2.
Since x∈(0,2], we have x−2≤0, so
∣f(x)∣=∣x−2∣=2−x.
- Compute h(x) piecewise
For −2≤x≤0
Here ∣x∣=−x, so
f(∣x∣)=∣x∣−2=−x−2.
Also,
∣f(x)∣=2.
Hence
h(x)=(−x−2)+2=−x.
For 0<x≤2
Here ∣x∣=x, so
f(∣x∣)=x−2.
Also,
∣f(x)∣=2−x.
Hence
h(x)=(x−2)+(2−x)=0.
So,
h(x)={−x,0,−2≤x≤0,0<x≤2.
(The value at x=0 is irrelevant for the integral.)
- Integrate
Therefore,
∫−22h(x)dx=∫−20(−x)dx+∫020dx.
Now,
∫−20(−x)dx=[−2x2]−20=0−(−24)=2.
And,
∫020dx=0.
Thus,
∫−22h(x)dx=2.
- Check options
The correct option is:
A: 2