The HCF of 15 and 28 is 1, making them coprime.

The distance from the origin to a point (x, y) is given by √(x² + y²). The point (0, 1) has a distance of 1, which is the smallest.

Substituting x = 2 into the equation y = 2(2) + 1 gives y = 5, so the point (2, 5) lies on the line.

A concave hexagon has at least one interior angle greater than 180 degrees, which makes it a non-convex polygon.

A star-shaped polygon has at least one interior angle greater than 180 degrees, making it concave.

The polynomial x^2 + 4x + 4 can be factored as (x + 2)^2, making it a perfect square.

A quadratic polynomial is defined as a polynomial of degree 2, which is 2x^2 + 3x - 5.

A rhombus has all sides equal and opposite angles equal.

A square has equal diagonals, which is a property of squares and rectangles.

In the equation y = mx + b, 'm' represents the slope of the line.

The sequence 2, 4, 8 does not have reciprocals that form an arithmetic progression, hence it cannot be a harmonic progression.

The sequence 2, 4, 8, 16 has a constant ratio of 2, making it a geometric progression.

The sequence 1, 1/2, 1/3 has reciprocals 1, 2, 3 which are in arithmetic progression, thus it is a harmonic progression.

An arithmetic progression has a constant difference between consecutive terms. The sequence 1, 3, 5, 7 has a common difference of 2.

The sum of probabilities of all possible outcomes must equal 1, which is a fundamental principle in probability theory.

In a parallelogram, the diagonals bisect each other, which is a defining property of parallelograms.

In a rectangle, opposite sides are equal and all angles are indeed 90 degrees.

The statement a^m + a^n = a^(m+n) is incorrect; addition of exponents does not apply in this manner.

In a geometric progression, the ratio of consecutive terms is indeed constant, which defines the progression.

In a harmonic progression, the terms can be negative as long as their reciprocals form an arithmetic progression.

All statements are true regarding multiples.

Base-2 can represent all integers, as it is a complete positional system.

Different numeral systems can represent the same value, such as the decimal 10 and binary 1010.

In a general partnership, partners can be held personally liable for the debts of the business.

Prime numbers are defined as numbers greater than 1 that have no divisors other than 1 and themselves.

A triangle has no diagonals, as it has only three vertices. The formula for the number of diagonals in a polygon is n(n-3)/2, where n is the number of sides.

The graph of a quadratic function is symmetric about its vertex.

30 is a multiple of 5, as it can be expressed as 5 multiplied by 6.

The sequence defined by a_n = 3n + 1 has a constant difference between consecutive terms, hence it is an arithmetic sequence.

The series consists of perfect squares: 1^2, 2^2, 3^2, 4^2, 5^2.