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Proofs

Proof means sufficient evidence to establish the truth of something. It is obtained from deductive reasoning, rather than from empirical arguments. Proof must show that a statement is true in all cases, without a single exception.

1,294 Questions

How can you prove that a residue class modulo prime is a multiplicative group?

To prove that the residue classes modulo a prime ( p ) form a multiplicative group, consider the set of non-zero integers modulo ( p ), denoted as ( \mathbb{Z}_p^* = { 1, 2, \ldots, p-1 } ). This set is closed under multiplication since the product of any two non-zero residues modulo ( p ) is also a non-zero residue modulo ( p ). The identity element is ( 1 ), and every element ( a ) in ( \mathbb{Z}_p^* ) has a multiplicative inverse ( b ) such that ( a \cdot b \equiv 1 \mod p ) (which exists due to ( p ) being prime). Thus, ( \mathbb{Z}_p^* ) satisfies the group properties of closure, associativity, identity, and inverses, confirming it is a multiplicative group.

Prove lim lnx equals - infinity x - 0 plus?

To prove that (\lim_{x \to 0^+} \ln x = -\infty), we can analyze the behavior of the natural logarithm function as (x) approaches 0 from the right. As (x) gets closer to 0, the value of (\ln x) decreases without bound, since the logarithm of values between 0 and 1 is negative and grows increasingly negative as (x) approaches 0. Thus, we conclude that (\lim_{x \to 0^+} \ln x = -\infty).

Is x on complement of real numbers is a binary operation?

No, the complement of real numbers is not a binary operation. A binary operation requires two elements from a set to produce a new element within the same set. The complement of the set of real numbers typically refers to elements not included in that set, which does not satisfy the criteria of producing a new element within the set of real numbers.

What is the principal of simplification A implies that B implies A?

The principle of simplification in logic states that if a statement A implies B, then A can be considered sufficient on its own to support the truth of B. This means that knowing A is true allows us to deduce that B must also be true. The statement can be expressed as "If A, then B" (A → B), and the idea is that the truth of A leads directly to the truth of B. Thus, in a logical framework, A serves as a premise from which B logically follows.

If two adjacent angles have their exterior sides in perpendicular lines the two angles are?

If two adjacent angles have their exterior sides in perpendicular lines, then the two angles are complementary. This means that the sum of their measures is 90 degrees. In this scenario, the angles share a common vertex and a side, while their other sides form a right angle with each other.

How many words per minutes 140 net keystrokes?

To convert net keystrokes into words per minute (WPM), you typically divide the total keystrokes by an average word length, often estimated at 5 characters per word, including spaces and punctuation. For 140 net keystrokes, this results in 140 ÷ 5 = 28 words. If this typing took one minute, that would equal 28 WPM.

What is the difference between simplex and dual simplex problem?

The simplex method is an algorithm used to solve linear programming problems, typically starting from a feasible solution and moving toward optimality by improving the objective function. In contrast, the dual simplex method begins with a feasible solution to the dual problem and iteratively adjusts the primal solution to maintain feasibility while improving the objective. The dual simplex is particularly useful when the primal solution is altered due to changes in constraints, allowing for efficient updates without reverting to a complete re-solution. Both methods ultimately aim to find the optimal solution but operate from different starting points and conditions.

What is P and q implies not not p or r if and only if q?

The statement "P and Q implies not not P or R if and only if Q" can be expressed in logical terms as ( (P \land Q) \implies (\neg \neg P \lor R) \iff Q ). This can be simplified, as (\neg \neg P) is equivalent to (P), leading to ( (P \land Q) \implies (P \lor R) \iff Q ). The implication essentially states that if both (P) and (Q) are true, then either (P) or (R) must also hold true, and this equivalence holds true only if (Q) is true. The overall expression reflects a relationship between the truth values of (P), (Q), and (R).

How do you prove that the group has no subgroup of order 6?

To prove that a group ( G ) has no subgroup of order 6, we can use the Sylow theorems. First, we note that if ( |G| ) is not divisible by 6, then ( G ) cannot have a subgroup of that order. If ( |G| ) is divisible by 6, we analyze the number of Sylow subgroups: the number of Sylow 2-subgroups ( n_2 ) must divide ( |G|/2 ) and be congruent to 1 modulo 2, while the number of Sylow 3-subgroups ( n_3 ) must divide ( |G|/3 ) and be congruent to 1 modulo 3. If both conditions cannot be satisfied simultaneously, it implies that no subgroup of order 6 exists.

Is any second category space a Baire space?

Yes, any second category space is a Baire space. A topological space is considered to be of second category if it cannot be expressed as a countable union of nowhere dense sets. Baire spaces are defined by the property that the intersection of countably many dense open sets is dense. Therefore, since second category spaces avoid being decomposed into countable unions of nowhere dense sets, they satisfy the conditions to be classified as Baire spaces.

That the height of the cone of maximum volume that can be inscribed in a sphere of radius 12cm is 16cm?

The height of the cone of maximum volume that can be inscribed in a sphere of radius 12 cm is not 16 cm; it is actually 16 cm when considering the relationship between the cone's dimensions and the sphere's radius. The cone's volume is maximized when its height is two-thirds of the sphere's radius, which means the optimal height is ( \frac{2}{3} \times 12 \text{ cm} = 8 \text{ cm} ). Thus, the statement is incorrect; the correct height for maximum volume is 8 cm, not 16 cm.

What is the first number that is invented?

The concept of numbers originated with the need for counting and measuring. The earliest known numeral system dates back to ancient Sumer in Mesopotamia around 3000 BCE, where symbols represented quantities. While it's difficult to pinpoint a single "first number," the number one (1) likely holds that distinction, as it represents the simplest form of counting—indicating a single unit or object.

Vjersha per 7 - 8 marsin?

7 Marsi

Festën e mësuesit

Ne do ta festojmë

Lulet më të bukura

Ne do ti dhurojmë.

Vijmë tek ti mësues

Buzëqeshjen ta dhurojmë

Kënga krahët reh si flutur

Midis jush jam e lumtur.

What is an estimate value and what is an actual value?

The difference between an estimate and an actual number is the difference between ideals and observations. For instance, You may think the time is 10:57, but in reality the probability of that is 0 due to the fact that time lies on a continuum. 10:57 is only an estimate; close enough for our purposes. The ideal: the actual time, is a theoretical ideal which we know must exist and be unique, but we can never know for certainty what it is.

What is the different between equal angles and congruent angles?

Two angles are congruent if they have the same shape and size, but are in different positions (for instance one may be rotated, flipped, or simply placed somewhere else). Equal is less precise term that just means the angles are the same. We often use equas to mean they have the same measure or number of degrees.

Why use phone number 555 555 5555?

Oh, dude, the classic 555 number! Yeah, that number is often used in movies and TV shows because it's not a real working number. So, if you see a character dialing 555 on screen, it's just a fake number to protect people's privacy. Like, imagine if every time someone in a movie gave out their number, they started getting calls from random fans or telemarketers. That would be a nightmare, right? So, 555 it is!

Postulate or theorem used to prove two triangles are congruent?

You can use a variety of postulates or theorems, among others:

SSS (Side-Side-Side)

ASA (Angle-Side-Angle - any two corresponding sides* and a corresponding angle)

SAS (Side-Angle-Side - the angle MUST be between the two sides, except:)

RHS (Right angle-Hypotenuse-Side - this is only ASS which works)

* if two corresponding angles are the same, then the third corresponding angle must also be the same (as the angles of a triangle always sum to 180°), and that can be substituted for one angle of ASA to get AAS or SAA.

What is the relationship between circles and triangles?

Circles and triangles are geometric shapes with distinct properties, but they can be related through various geometric principles. For example, a circle can be inscribed in a triangle or a triangle can be inscribed in a circle. Additionally, the circumcircle of a triangle is a circle that passes through all three vertices of the triangle. These relationships demonstrate the interconnected nature of geometric shapes and the principles that govern their properties.

Show that a xor b a union b - a intersect b?

To show that ( A \oplus B = (A \cup B) - (A \cap B) ), we need to prove two inclusions.

For the first inclusion, let ( x \in A \oplus B ). This means that ( x ) is in exactly one of ( A ) or ( B ), but not both. Therefore, ( x ) is in ( A ) or ( B ), but not in their intersection. Hence, ( x \in (A \cup B) - (A \cap B) ).

For the second inclusion, let ( x \in (A \cup B) - (A \cap B) ). This means that ( x ) is in either ( A ) or ( B ), but not in their intersection. Thus, ( x ) is in exactly one of ( A ) or ( B ), leading to ( x \in A \oplus B ).

Therefore, we have shown that ( A \oplus B = (A \cup B) - (A \cap B) ).

If x is an integer divisible by 3 then is x2 divisible by 3?

Yes, if x is an integer divisible by 3, then x^2 is also divisible by 3. This is because for any integer x, x^2 will also be divisible by 3 if x is divisible by 3. This can be proven using the property that the square of any integer divisible by 3 will also be divisible by 3.

Is the 2 square root of 5 rational or irrational why?

It is irrational.

The proof depends on the proof that sqrt(5) is irrational. However, judging by this question, I suggest that you are not yet ready for that proof.

So, assume that sqrt(5) is irrational. Any multiple of an irrrational number by a non-zero rational isirrational.

For suppose 2*sqrt(5) were rational

that is 2*sqrt(5) = p/q for some integers p and q, where q is nonzero.

then dividing both isdes by 2 gives sqrt(5) = p/(2q) where p and 2q are both integers and 2q in non-zero.

But that implies that sqrt(5) is rational!

That is a contradiction so 2*sqrt(5) cannot be rational.

How do you know if two matrices can actually be multiplied?

The number of columns in the first matrix must equal the number of rows in the second.

Is there a formula to work out trigonometry?

No, because trigonometry is a big subject: there are many formulae.

The next lemma is an analog of the previous lemma?

This usually means the upcoming lemma is an adaption of a previous lemma to a mathematical object related to the one in the first lemma.