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Let and be differentiable functions such that for every real
MATHEMATICS · Subjective · A Level · Mathematics · Proof · Proof
Problem
Let
f
(
x
)
f(x)
f
(
x
)
and
g
(
x
)
g(x)
g
(
x
)
be differentiable functions such that
f
′
(
x
)
g
(
x
)
≠
f
(
x
)
g
′
(
x
)
f'(x)g(x)\ne f(x)g'(x)
f
′
(
x
)
g
(
x
)
=
f
(
x
)
g
′
(
x
)
for every real
x
x
x
. Show that between any two real solutions of
f
(
x
)
=
0
f(x)=0
f
(
x
)
=
0
, there is at least one real solution of
g
(
x
)
=
0
g(x)=0
g
(
x
)
=
0
.
Related theory
Derivative Foundations
Mathematical Logic
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