MathDB
Problems
Contests
Undergraduate contests
Vojtěch Jarník IMC
2013 VJIMC
Problem 4
integral of f(t)/(sqrt(x-t))
integral of f(t)/(sqrt(x-t))
Source: VJIMC 2013 2.4
May 30, 2021
calculus
integration
Problem Statement
Let
F
\mathcal F
F
be the set of all continuous functions
f
:
[
0
,
1
]
→
R
f:[0,1]\to\mathbb R
f
:
[
0
,
1
]
→
R
with the property
∣
∫
0
x
f
(
t
)
x
−
t
d
t
∣
≤
1
for all
x
∈
(
0
,
1
]
.
\left|\int^x_0\frac{f(t)}{\sqrt{x-t}}\text dt\right|\le1\enspace\text{for all }x\in(0,1].
∫
0
x
x
−
t
f
(
t
)
d
t
≤
1
for all
x
∈
(
0
,
1
]
.
Compute
sup
f
∈
F
∣
∫
0
1
f
(
x
)
d
x
∣
\sup_{f\in\mathcal F}\left|\int^1_0f(x)\text dx\right|
sup
f
∈
F
∫
0
1
f
(
x
)
d
x
.
Back to Problems
View on AoPS