At every x , the curve takes the larger value of
y 1 = | x | , y 2 = x | x − 2 | .
So we must determine which function lies above on different intervals.
(i) Interval x < 0
| x | = − x , | x − 2 | = 2 − x
x | x − 2 | = x ( 2 − x ) = 2 x − x 2 < 0
Since | x | > 0 and x | x − 2 | < 0 ,
Max = | x | on [ − 2 , 0 ] .
(ii) Interval 0 ≤ x ≤ 2
Here
| x | = x , x | x − 2 | = x ( 2 − x ) .
Compare:
x ( 2 − x ) ≥ x ⇒ x ( 1 − x ) ≥ 0
This holds for 0 ≤ x ≤ 1 .
Hence
0 ≤ x ≤ 1 : max = 2 x − x 2
1 ≤ x ≤ 2 : max = x
(iii) Interval x ≥ 2
|x|=x, x|x-2|=x(x-2)
x ( x − 2 ) ≥ x ⇒ x ( x − 3 ) ≥ 0
True for x ≥ 3 .
So
2 ≤ x ≤ 3 : max = x
3 ≤ x ≤ 4 : max = x 2 − 2 x
So, Area as a piecewise integral
A = ∫ − 2 0 | x | d x + ∫ 0 1 ( 2 x − x 2 ) d x + ∫ 1 3 x d x + ∫ 3 4 ( x 2 − 2 x ) d x
= 2 + 2 3 + 4 + 16 3
= 12 Square Units
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