∃x∈R,(x+ 1 = 0 x+ 2 = 0)
(∃x∈R, x + 1 = 0) (∃x∈R, x + 2 = 0)
∀x∈R,(x+ 1 6= 0 x+ 2 6= 0)
∃x∈R∗,∀y∈R∗,∀z∈R∗, z −xy = 0
∀y∈R∗,∃x∈R∗,∀z∈R∗, z −xy = 0
∀y∈R∗,∀z∈R∗,∃x∈R∗, z −xy = 0
∃a∈R,∀ε > 0,|a|< ε
∀ε > 0,∃a∈R,|a|< ε
∀x∈R,∀y∈R, x =y.
∃x∈R,∃y∈R, x =y.
∃x∈R,∀y∈R, x =y.
∀x∈R,∃y∈R, x =y.
f:R→R
∀x∈R,∃y∈R, y =f(x)
∃y∈R,∀x∈R, y =f(x)
f:R→R
∀x∈R, f(x)6= 0.
∀M > 0,∃A > 0,∀x>A, f(x)> M.
∀x∈R, f(x)>0⇒x60.
f:R→R
f
f
fR
∀x∈R,∃y∈R, x =y.
n∈Nn2n
∀n∈N,n(n2+ 1)
2∈N.