English
If x, y ≥ 0 in EReal, then (x + y).toENNReal = x.toENNReal + y.toENNReal.
Русский
Если x, y \\\\ge 0 в EReal, тогда (x+y).toENNReal = x.toENNReal + y.toENNReal.
LaTeX
$$$\\\\forall {x,y \\\\in \\\\mathrm{EReal}},\\\\ x \\\\ge 0 \\\\land y \\\\ge 0 \\\\Rightarrow (x+y).toENNReal = x.toENNReal + y.toENNReal$$$
Lean4
theorem toENNReal_add {x y : EReal} (hx : 0 ≤ x) (hy : 0 ≤ y) : (x + y).toENNReal = x.toENNReal + y.toENNReal :=
by
induction x <;> induction y <;>
try { · simp_all
}
norm_cast
simp_rw [real_coe_toENNReal]
simp_all [ENNReal.ofReal_add]