Step |
Hyp |
Ref |
Expression |
1 |
|
requad2.a |
⊢ ( 𝜑 → 𝐴 ∈ ℝ ) |
2 |
|
requad2.z |
⊢ ( 𝜑 → 𝐴 ≠ 0 ) |
3 |
|
requad2.b |
⊢ ( 𝜑 → 𝐵 ∈ ℝ ) |
4 |
|
requad2.c |
⊢ ( 𝜑 → 𝐶 ∈ ℝ ) |
5 |
|
requad2.d |
⊢ ( 𝜑 → 𝐷 = ( ( 𝐵 ↑ 2 ) − ( 4 · ( 𝐴 · 𝐶 ) ) ) ) |
6 |
1
|
recnd |
⊢ ( 𝜑 → 𝐴 ∈ ℂ ) |
7 |
6
|
ad2antrr |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → 𝐴 ∈ ℂ ) |
8 |
2
|
ad2antrr |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → 𝐴 ≠ 0 ) |
9 |
3
|
recnd |
⊢ ( 𝜑 → 𝐵 ∈ ℂ ) |
10 |
9
|
ad2antrr |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → 𝐵 ∈ ℂ ) |
11 |
4
|
recnd |
⊢ ( 𝜑 → 𝐶 ∈ ℂ ) |
12 |
11
|
ad2antrr |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → 𝐶 ∈ ℂ ) |
13 |
|
recn |
⊢ ( 𝑥 ∈ ℝ → 𝑥 ∈ ℂ ) |
14 |
13
|
adantl |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → 𝑥 ∈ ℂ ) |
15 |
5
|
ad2antrr |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → 𝐷 = ( ( 𝐵 ↑ 2 ) − ( 4 · ( 𝐴 · 𝐶 ) ) ) ) |
16 |
7 8 10 12 14 15
|
quad |
⊢ ( ( ( 𝜑 ∧ 0 ≤ 𝐷 ) ∧ 𝑥 ∈ ℝ ) → ( ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ ( 𝑥 = ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∨ 𝑥 = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ) ) ) |
17 |
16
|
reubidva |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ ∃! 𝑥 ∈ ℝ ( 𝑥 = ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∨ 𝑥 = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ) ) ) |
18 |
3
|
renegcld |
⊢ ( 𝜑 → - 𝐵 ∈ ℝ ) |
19 |
18
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → - 𝐵 ∈ ℝ ) |
20 |
3
|
resqcld |
⊢ ( 𝜑 → ( 𝐵 ↑ 2 ) ∈ ℝ ) |
21 |
|
4re |
⊢ 4 ∈ ℝ |
22 |
21
|
a1i |
⊢ ( 𝜑 → 4 ∈ ℝ ) |
23 |
1 4
|
remulcld |
⊢ ( 𝜑 → ( 𝐴 · 𝐶 ) ∈ ℝ ) |
24 |
22 23
|
remulcld |
⊢ ( 𝜑 → ( 4 · ( 𝐴 · 𝐶 ) ) ∈ ℝ ) |
25 |
20 24
|
resubcld |
⊢ ( 𝜑 → ( ( 𝐵 ↑ 2 ) − ( 4 · ( 𝐴 · 𝐶 ) ) ) ∈ ℝ ) |
26 |
5 25
|
eqeltrd |
⊢ ( 𝜑 → 𝐷 ∈ ℝ ) |
27 |
|
resqrtcl |
⊢ ( ( 𝐷 ∈ ℝ ∧ 0 ≤ 𝐷 ) → ( √ ‘ 𝐷 ) ∈ ℝ ) |
28 |
26 27
|
sylan |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( √ ‘ 𝐷 ) ∈ ℝ ) |
29 |
19 28
|
readdcld |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( - 𝐵 + ( √ ‘ 𝐷 ) ) ∈ ℝ ) |
30 |
|
2re |
⊢ 2 ∈ ℝ |
31 |
30
|
a1i |
⊢ ( 𝜑 → 2 ∈ ℝ ) |
32 |
31 1
|
remulcld |
⊢ ( 𝜑 → ( 2 · 𝐴 ) ∈ ℝ ) |
33 |
32
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( 2 · 𝐴 ) ∈ ℝ ) |
34 |
|
2cnd |
⊢ ( 𝜑 → 2 ∈ ℂ ) |
35 |
|
2ne0 |
⊢ 2 ≠ 0 |
36 |
35
|
a1i |
⊢ ( 𝜑 → 2 ≠ 0 ) |
37 |
34 6 36 2
|
mulne0d |
⊢ ( 𝜑 → ( 2 · 𝐴 ) ≠ 0 ) |
38 |
37
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( 2 · 𝐴 ) ≠ 0 ) |
39 |
29 33 38
|
redivcld |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∈ ℝ ) |
40 |
19 28
|
resubcld |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( - 𝐵 − ( √ ‘ 𝐷 ) ) ∈ ℝ ) |
41 |
40 33 38
|
redivcld |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∈ ℝ ) |
42 |
|
euoreqb |
⊢ ( ( ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∈ ℝ ∧ ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∈ ℝ ) → ( ∃! 𝑥 ∈ ℝ ( 𝑥 = ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∨ 𝑥 = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ) ↔ ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ) ) |
43 |
39 41 42
|
syl2anc |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ∃! 𝑥 ∈ ℝ ( 𝑥 = ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ∨ 𝑥 = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ) ↔ ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ) ) |
44 |
9
|
negcld |
⊢ ( 𝜑 → - 𝐵 ∈ ℂ ) |
45 |
26
|
recnd |
⊢ ( 𝜑 → 𝐷 ∈ ℂ ) |
46 |
45
|
sqrtcld |
⊢ ( 𝜑 → ( √ ‘ 𝐷 ) ∈ ℂ ) |
47 |
32
|
recnd |
⊢ ( 𝜑 → ( 2 · 𝐴 ) ∈ ℂ ) |
48 |
44 46 47 37
|
divdird |
⊢ ( 𝜑 → ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
49 |
48
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
50 |
44 46 47 37
|
divsubdird |
⊢ ( 𝜑 → ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) − ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
51 |
50
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) − ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
52 |
44 47 37
|
divcld |
⊢ ( 𝜑 → ( - 𝐵 / ( 2 · 𝐴 ) ) ∈ ℂ ) |
53 |
52
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( - 𝐵 / ( 2 · 𝐴 ) ) ∈ ℂ ) |
54 |
46 47 37
|
divcld |
⊢ ( 𝜑 → ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ∈ ℂ ) |
55 |
54
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ∈ ℂ ) |
56 |
53 55
|
negsubd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 / ( 2 · 𝐴 ) ) + - ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) − ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
57 |
46
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( √ ‘ 𝐷 ) ∈ ℂ ) |
58 |
47
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( 2 · 𝐴 ) ∈ ℂ ) |
59 |
57 58 38
|
divnegd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → - ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) = ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) |
60 |
59
|
oveq2d |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 / ( 2 · 𝐴 ) ) + - ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
61 |
51 56 60
|
3eqtr2d |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
62 |
49 61
|
eqeq12d |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ↔ ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) ) |
63 |
46
|
negcld |
⊢ ( 𝜑 → - ( √ ‘ 𝐷 ) ∈ ℂ ) |
64 |
63 47 37
|
divcld |
⊢ ( 𝜑 → ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ∈ ℂ ) |
65 |
64
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ∈ ℂ ) |
66 |
53 55 65
|
addcand |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ↔ ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) = ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ) |
67 |
|
div11 |
⊢ ( ( ( √ ‘ 𝐷 ) ∈ ℂ ∧ - ( √ ‘ 𝐷 ) ∈ ℂ ∧ ( ( 2 · 𝐴 ) ∈ ℂ ∧ ( 2 · 𝐴 ) ≠ 0 ) ) → ( ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) = ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ↔ ( √ ‘ 𝐷 ) = - ( √ ‘ 𝐷 ) ) ) |
68 |
46 63 47 37 67
|
syl112anc |
⊢ ( 𝜑 → ( ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) = ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ↔ ( √ ‘ 𝐷 ) = - ( √ ‘ 𝐷 ) ) ) |
69 |
68
|
adantr |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) = ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ↔ ( √ ‘ 𝐷 ) = - ( √ ‘ 𝐷 ) ) ) |
70 |
57
|
eqnegd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( √ ‘ 𝐷 ) = - ( √ ‘ 𝐷 ) ↔ ( √ ‘ 𝐷 ) = 0 ) ) |
71 |
|
sqrt00 |
⊢ ( ( 𝐷 ∈ ℝ ∧ 0 ≤ 𝐷 ) → ( ( √ ‘ 𝐷 ) = 0 ↔ 𝐷 = 0 ) ) |
72 |
26 71
|
sylan |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( √ ‘ 𝐷 ) = 0 ↔ 𝐷 = 0 ) ) |
73 |
70 72
|
bitrd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( √ ‘ 𝐷 ) = - ( √ ‘ 𝐷 ) ↔ 𝐷 = 0 ) ) |
74 |
66 69 73
|
3bitrd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) = ( ( - 𝐵 / ( 2 · 𝐴 ) ) + ( - ( √ ‘ 𝐷 ) / ( 2 · 𝐴 ) ) ) ↔ 𝐷 = 0 ) ) |
75 |
62 74
|
bitrd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ( ( - 𝐵 + ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) = ( ( - 𝐵 − ( √ ‘ 𝐷 ) ) / ( 2 · 𝐴 ) ) ↔ 𝐷 = 0 ) ) |
76 |
17 43 75
|
3bitrd |
⊢ ( ( 𝜑 ∧ 0 ≤ 𝐷 ) → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ 𝐷 = 0 ) ) |
77 |
76
|
expcom |
⊢ ( 0 ≤ 𝐷 → ( 𝜑 → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ 𝐷 = 0 ) ) ) |
78 |
1 2 3 4 5
|
requad01 |
⊢ ( 𝜑 → ( ∃ 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ 0 ≤ 𝐷 ) ) |
79 |
78
|
notbid |
⊢ ( 𝜑 → ( ¬ ∃ 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ ¬ 0 ≤ 𝐷 ) ) |
80 |
79
|
biimparc |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → ¬ ∃ 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ) |
81 |
|
reurex |
⊢ ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 → ∃ 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ) |
82 |
80 81
|
nsyl |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → ¬ ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ) |
83 |
82
|
pm2.21d |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 → 𝐷 = 0 ) ) |
84 |
|
0red |
⊢ ( 𝜑 → 0 ∈ ℝ ) |
85 |
26 84
|
ltnled |
⊢ ( 𝜑 → ( 𝐷 < 0 ↔ ¬ 0 ≤ 𝐷 ) ) |
86 |
85
|
biimparc |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → 𝐷 < 0 ) |
87 |
86
|
lt0ne0d |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → 𝐷 ≠ 0 ) |
88 |
|
eqneqall |
⊢ ( 𝐷 = 0 → ( 𝐷 ≠ 0 → ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ) ) |
89 |
87 88
|
syl5com |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → ( 𝐷 = 0 → ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ) ) |
90 |
83 89
|
impbid |
⊢ ( ( ¬ 0 ≤ 𝐷 ∧ 𝜑 ) → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ 𝐷 = 0 ) ) |
91 |
90
|
ex |
⊢ ( ¬ 0 ≤ 𝐷 → ( 𝜑 → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ 𝐷 = 0 ) ) ) |
92 |
77 91
|
pm2.61i |
⊢ ( 𝜑 → ( ∃! 𝑥 ∈ ℝ ( ( 𝐴 · ( 𝑥 ↑ 2 ) ) + ( ( 𝐵 · 𝑥 ) + 𝐶 ) ) = 0 ↔ 𝐷 = 0 ) ) |