Conseils de rédaction

x, t, n, a, f, i, A, F, α, φ, N
f(x)>0
(an)C
f x (an)C
x f
(an)k 
N R
x∈R
x∈R
∀ > 0∈R∗
+
x∈Rcos x= sin x
x∈[0, π] cos x= sin x

[0, π]
x
x∈Rx
x P
∀x∈R,cos(x−(π/2)) = sin x
x∈Rcos((π/2) −x) = sin x
∃x∈R,cos x= sin x
∃x∈[0, π],cos x= sin x
∀x∈[0, π],((cos x= sin x)⇒x=π/4)
x∈[0, π] cos x= sin x x =π/4
∀ > 0,∃x > 0, x/(x+ 1) >1−
x
(cos x= sin x)⇒x=π/4
(cos x= sin x)⇒x= (π/4) + kπ
x k
f
x

f(x)
∃x∈[0, π],cos x= sin x x =π/4
[0, π]
x
(∃x∈[0, π],cos x= sin x)x
[0, π]x x
[0, π]
xcos x= sin x x
tan x= 1
∃x∈Rcos x= sin x
⇒tan x= 1
(∃x∈R,cos x= sin x)
⇒(∃x∈R,tan x= 1)
cos(x−(π/2)) = sin x x ∈R
f:R→R
∀x∈R,∀y∈R,∀ > 0,∃η > 0,(|x−y|< η ⇒ |f(x)−f(y)|< ).
⇒ ⇔
⇒ ⇔

⇒ ⇔
(∀x∈E, f(x) = g(x)⇒f=g)
(∀x∈E, f(x) = g(x)) ⇒f=g,
∀x∈E, (f(x) = g(x)⇒f=g).
⇒ ⇔
∀x∈[0, π[,∀n∈N,sin(nx)<1/2⇒x= 0.
x∈E f(x) = g(x)f=g
x∈E f(x) = g(x)f=g
x∈[0, π[n∈Nsin (nx)<1
2x= 0
(P⇒Q)P Q P
Q P Q
P P
Q
⇔
⇒ ⇐