Metamath Proof Explorer


Theorem mulgp1

Description: Group multiple (exponentiation) operation at a successor, extended to ZZ . (Contributed by Mario Carneiro, 11-Dec-2014)

Ref Expression
Hypotheses mulgnndir.b 𝐵 = ( Base ‘ 𝐺 )
mulgnndir.t · = ( .g𝐺 )
mulgnndir.p + = ( +g𝐺 )
Assertion mulgp1 ( ( 𝐺 ∈ Grp ∧ 𝑁 ∈ ℤ ∧ 𝑋𝐵 ) → ( ( 𝑁 + 1 ) · 𝑋 ) = ( ( 𝑁 · 𝑋 ) + 𝑋 ) )

Proof

Step Hyp Ref Expression
1 mulgnndir.b 𝐵 = ( Base ‘ 𝐺 )
2 mulgnndir.t · = ( .g𝐺 )
3 mulgnndir.p + = ( +g𝐺 )
4 1z 1 ∈ ℤ
5 1 2 3 mulgdir ( ( 𝐺 ∈ Grp ∧ ( 𝑁 ∈ ℤ ∧ 1 ∈ ℤ ∧ 𝑋𝐵 ) ) → ( ( 𝑁 + 1 ) · 𝑋 ) = ( ( 𝑁 · 𝑋 ) + ( 1 · 𝑋 ) ) )
6 4 5 mp3anr2 ( ( 𝐺 ∈ Grp ∧ ( 𝑁 ∈ ℤ ∧ 𝑋𝐵 ) ) → ( ( 𝑁 + 1 ) · 𝑋 ) = ( ( 𝑁 · 𝑋 ) + ( 1 · 𝑋 ) ) )
7 6 3impb ( ( 𝐺 ∈ Grp ∧ 𝑁 ∈ ℤ ∧ 𝑋𝐵 ) → ( ( 𝑁 + 1 ) · 𝑋 ) = ( ( 𝑁 · 𝑋 ) + ( 1 · 𝑋 ) ) )
8 1 2 mulg1 ( 𝑋𝐵 → ( 1 · 𝑋 ) = 𝑋 )
9 8 3ad2ant3 ( ( 𝐺 ∈ Grp ∧ 𝑁 ∈ ℤ ∧ 𝑋𝐵 ) → ( 1 · 𝑋 ) = 𝑋 )
10 9 oveq2d ( ( 𝐺 ∈ Grp ∧ 𝑁 ∈ ℤ ∧ 𝑋𝐵 ) → ( ( 𝑁 · 𝑋 ) + ( 1 · 𝑋 ) ) = ( ( 𝑁 · 𝑋 ) + 𝑋 ) )
11 7 10 eqtrd ( ( 𝐺 ∈ Grp ∧ 𝑁 ∈ ℤ ∧ 𝑋𝐵 ) → ( ( 𝑁 + 1 ) · 𝑋 ) = ( ( 𝑁 · 𝑋 ) + 𝑋 ) )