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2023 UMD Math Competition Part I
#21
Least possible value
Least possible value
Source: UMD 2023 I #21
October 22, 2023
algebra
UMD
Problem Statement
Let
a
,
b
,
c
,
d
,
e
a, b, c, d, e
a
,
b
,
c
,
d
,
e
be real numbers such that
a
<
b
<
c
<
d
<
e
.
a<b<c<d<e.
a
<
b
<
c
<
d
<
e
.
The least possible value of the function
f
:
R
→
R
f: \mathbb R \to \mathbb R
f
:
R
→
R
with
f
(
x
)
=
∣
x
−
a
∣
+
∣
x
−
b
∣
+
∣
x
−
c
∣
+
∣
x
−
d
∣
+
∣
x
−
e
∣
f(x) = |x-a| + |x - b|+ |x - c| + |x - d|+ |x - e|
f
(
x
)
=
∣
x
−
a
∣
+
∣
x
−
b
∣
+
∣
x
−
c
∣
+
∣
x
−
d
∣
+
∣
x
−
e
∣
is
a
.
e
+
d
+
c
+
b
+
a
b
.
e
+
d
+
c
−
b
−
a
c
.
e
+
d
+
∣
c
∣
−
b
−
a
d
.
e
+
d
+
b
−
a
e
.
e
+
d
−
b
−
a
\mathrm a. ~ e+d+c+b+a\qquad \mathrm b.~e+d+c-b-a\qquad \mathrm c. ~e+d+|c|-b-a \qquad \mathrm d. ~e+d+b-a \qquad \mathrm e. ~e+d-b-a
a
.
e
+
d
+
c
+
b
+
a
b
.
e
+
d
+
c
−
b
−
a
c
.
e
+
d
+
∣
c
∣
−
b
−
a
d
.
e
+
d
+
b
−
a
e
.
e
+
d
−
b
−
a
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