Theorem: inv_eq_of_root_of_coeff_zero_ne_zero
File: Mathlib/RingTheory/Algebraic.lean

Proof steps:
state_before: R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
⊢ x⁻¹ = -((aeval x) p.divX / (algebraMap K L) (p.coeff 0))
state_after: case h.e'_3
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
⊢ -((aeval x) p.divX / (algebraMap K L) (p.coeff 0)) = (aeval x) p.divX / ((aeval x) p - (algebraMap K L) (p.coeff 0))

case convert_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = (algebraMap K L) 0
tactic: convert inv_eq_of_aeval_divX_ne_zero (p := p) (L := L)
    (mt (fun h => (algebraMap K L).injective ?_) coeff_zero_ne) using 1
state_before: case convert_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = (algebraMap K L) 0
state_after: case convert_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = 0
tactic: rw [RingHom.map_zero]
state_before: case convert_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = 0
state_after: case h.e'_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = (aeval x) p
tactic: convert aeval_eq
state_before: case h.e'_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = (aeval x) p
state_after: case h.e'_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = (aeval x) (p.divX * X + C (p.coeff 0))
tactic: conv_rhs => rw [← divX_mul_X_add p]
state_before: case h.e'_2
R : Type u_1
S : Type u_2
inst✝⁵ : CommRing R
inst✝⁴ : IsDomain R
inst✝³ : CommRing S
K : Type u_3
L : Type u_4
inst✝² : Field K
inst✝¹ : Field L
inst✝ : Algebra K L
A : Subalgebra K L
x : L
p : K[X]
aeval_eq : (aeval x) p = 0
coeff_zero_ne : p.coeff 0 ≠ 0
h : (aeval x) p.divX = 0
⊢ (algebraMap K L) (p.coeff 0) = (aeval x) (p.divX * X + C (p.coeff 0))
state_after: no goals
tactic: rw [map_add, map_mul, h, zero_mul, zero_add, aeval_C]