Proofs

A proof is a series of claims that lead to a conclusion. Some proofs are conditional, which means that the claims can only be made under certain conditions. Click on a statement to see the proof

Algebra 16
(a ⋅ (s / 2)) / s = a / 2

Divide Zero 2
if b > 0, then (c - c) / ((b + a) - a) = 0

Algebra 19
if the following are true:
  • a = b + c
  • x = y + z
  • a = x
  • b = z

then c = y


Substitute Two Numbers
if the following are true:
  • a = b + c
  • b = x
  • c = y

then a = x + y


Commutative Property Variation 1
if a = b + c, then a = c + b

Commutative Property Example 2
if a + b = c, then b + a = c

Term 2 Substitution
if the following are true:
  • a = b + c
  • c = d

then a = b + d


Substitution 3
if the following are true:
  • a = b + c
  • d = c

then a = b + d


Substitution 4
if a = b, then (ac) + d = (bc) + d

Add Negative B
if a = b, then a + (b ⋅ (-1)) = 0

Add Term to Both Sides
if a = b, then c + a = c + b

Add Term to Both Sides 2
if a = b, then c + b = c + a

Add Term to Both Sides 3
if a = b, then b + c = a + c

Equality Example
if the following are true:
  • a = b
  • c = d

then a + c = b + d


Add Terms Twice
if x = y, then (a + x) + c = (a + y) + c

Add Substitute Term
if the following are true:
  • x = y
  • (a + x) + c = f

then (a + y) + c = f


Subtract Same Sides
if the following are true:
  • a = b
  • c = d

then a - c = b - d


Subtract From Both Sides
if a = b, then b - c = a - c

Subtract From Both Sides Mirror
if a = b, then a - c = b - c

Substitute
if the following are true:
  • a = b
  • f = b - c

then f = a - c


Substitute Two Terms
if the following are true:
  • a = b
  • c = d
  • f = a - c

then f = b - d


Multiply And Subtract Each Side
if a = b, then (ac) - d = (bc) - d

Multiplicative Property of Equality Variation 2
if a = b, then cb = ca

Multiplicative Property of Equality Variation 1
if a = b, then ca = cb

First Term Substitution
if the following are true:
  • a = bc
  • b = d

then a = dc


Substitution 12
if the following are true:
  • a = bc
  • c = d

then a = bd


Substitution 13
if the following are true:
  • a = x
  • b = xy

then b = ay


Substitution 14
if the following are true:
  • x = a
  • xy = b

then ay = b


Substitution in Product
if the following are true:
  • ab = c
  • b = d

then ad = c


Divide Both Sides
if a = b, then a / c = b / c

Multiply Substitute Two Terms
if the following are true:
  • a = x
  • c = y

then (a + c) / m = (x + y) / m


Multiply Substitute Two Terms 2
if the following are true:
  • a = x
  • c = y
  • s = (a + c) / m

then s = (x + y) / m


Subtract Both Sides
if a = b + c, then a + (c ⋅ (-1)) = b

Subtract Both Sides 2
if a = b + c, then a + (b ⋅ (-1)) = c

Substitution 5
if the following are true:
  • a = b + c
  • a = d

then d = b + c


Term 1 Substitution
if the following are true:
  • a = b + c
  • b = d

then a = d + c


Substitution 7
if the following are true:
  • a = b + c
  • d = b

then a = d + c


Subtract Number
if a = 360 + (180 ⋅ (-1)), then a = 180

Subtraction Example 2
if y = 180 + (90 ⋅ (-1)), then y = 90

Subtract Number 3
if 180 + (90 ⋅ (-1)) = y, then 90 = y

Add Number to Both Sides
if a + 90 = 180, then a = 90

Add Number to Both Sides 2
if 90 + a = 180, then a = 90

Add Number to Both Sides 3
if 180 = 90 + a, then a = 90

Divide 180 by 2
if a = 180 ⋅ (1 / 2), then a = 90

Add Two 90
if the following are true:
  • a = 90
  • b = 90

then a + b = 180


Substitute 6
if the following are true:
  • a = ((b + c) + d) + e
  • d + e = f

then a = (b + c) + f


Substitute 7
if the following are true:
  • a + (b ⋅ (-1)) = c
  • b = d

then a + (d ⋅ (-1)) = c


Add Term to Both Sides 7
if a + b = c, then b = c + (a ⋅ (-1))

Substitution 8
if the following are true:
  • a + b = c
  • a = d

then d + b = c


Substitute 9
if the following are true:
  • a + b = c
  • d = a

then d + b = c


Substitution Example 10
if the following are true:
  • a + b = c
  • b = d

then a + d = c


Substitute 2
if the following are true:
  • a + b = c
  • d = b

then a + d = c


Add Term to Both Sides 6
if a + b = c, then a = c + (b ⋅ (-1))

Add Term to Both Sides 5
if a + b = c, then b = c + (a ⋅ (-1))

Subtract Equation
if a + b = c, then a = c - b

Subtract Equation 2
if a + b = c, then b = c - a

Substitute First Term
if the following are true:
  • (a + b) + c = d
  • a = e

then (e + b) + c = d


Add Term to Both Sides 4
if (a + b) + c = d, then b + c = d + (a ⋅ (-1))

Substitution in the Middle
if a + b = c, then ((x + a) + b) + y = (x + c) + y

Sum Equation
if (a + b) + c = d, then a + c = d - b

Divide Both
if the following are true:
  • a / b = c / d
  • d = e

then a / b = c / e


Divide Substitute
if the following are true:
  • a = b / c
  • b = d

then a = d / c


Divide Substitute 2
if the following are true:
  • a = x
  • b = y

then a / b = x / y


Divide New
if the following are true:
  • a / b = c
  • d = a

then c = d / b


Divide New B
if the following are true:
  • c = a / b
  • d = a

then c = d / b


Divide New 2
if the following are true:
  • a / b = c
  • d = a

then d / b = c


Divide Substitute 4
if the following are true:
  • a = w
  • b = x
  • c = y
  • d = z

then (a - b) / (c - d) = (w - x) / (y - z)


Whole is Greater Than Parts
if the following are true:
  • a = b + c
  • b > 0

then a > c


Slope 1
if the following are true:
  • f = (a - b) / (c - d)
  • a = w
  • b = x
  • c = y
  • d = z

then f = (w - x) / (y - z)


Add One
sum of (list 0 and (empty list)) (list 0 and (empty list)) and carry bit 0 = list 0 and (empty list)

Add Two
sum of unsigned integers (list 1 and (empty list)) and (list 1 and (empty list)) = list 0 and (list 1 and (empty list))

Add Three Uints
sum of unsigned integers (list 1 and (list 1 and (empty list))) and (list 1 and (list 1 and (empty list))) = list 0 and (list 1 and (list 1 and (empty list)))

Add Three by Zero
sum of unsigned integers (list 1 and (list 1 and (empty list))) and (list 0 and (empty list)) = list 1 and (list 1 and (empty list))

Add by Zero
sum of unsigned integers (list x and xs) and (list 0 and (empty list)) = list x and xs

Multiply Two
(list 1 and (list 1 and (empty list))) multiplied by (list 0 and (list 1 and (empty list))) = list 0 and (list 1 and (list 1 and (empty list)))

Multiply by Two
(list x and xs) multiplied by (list 0 and (list 1 and (empty list))) = sum of unsigned integers (list x and xs) and (list x and xs)

Associative
a + (b + c) = (a + b) + c

Additive Identity Variation
0 + a = a

Subtract Commutative
(a ⋅ (-1)) + a = 0

Subtract Commutative 2
((-1) ⋅ a) + a = 0

Subtraction Example
a + (b ⋅ (-1)) = a - b

Subtract to Zero
a - a = 0

Subtract Zero Example
a - 0 = a

Subtract Associative
(a + b) - c = a + (b - c)

Subtract 1
(b + a) - a = b

Multiplicative Identity 2
a = a1

Multiplicative Identity 3
1a = a

Distributive Property Variation 2
(b + c) ⋅ a = (ab) + (ac)

Distributive Property Variation 3
(a + b) ⋅ c = (ac) + (bc)

Distributive Property Variation 4
(ab) + (ac) = a ⋅ (b + c)

Distributive Property 5
(ac) + (bc) = (a + b) ⋅ c

Division Theorem
a ⋅ (1 / b) = a / b

Division is Commutative
a ⋅ (b / c) = (ab) / c

Associative Property
(ab) / c = a ⋅ (b / c)

Associative Property of Multiplication 2
a ⋅ (bc) = (ab) ⋅ c

Swap 2 and 3 Theorem
(ab) ⋅ c = (ac) ⋅ b

Multiply Reorder 2
(ab) ⋅ c = (bc) ⋅ a

Distribute Subtract
(a - b) ⋅ c = (ac) - (bc)

Add Associative
((a + b) + c) + d = a + ((b + c) + d)

Add Associative 2
(a + b) + c = (a + c) + b


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