Similar triangles have equal corresponding angles, but their sides are in proportion, not necessarily equal.

A quadratic equation is one that can be expressed in the form ax^2 + bx + c = 0, which is satisfied by x^2 - 4x + 4 = 0.

The roots of the polynomial can be found by factoring it as (x-2)(x-3) = 0, giving roots 2 and 3.

A number is divisible by 11 if the difference between the sum of the digits in odd positions and the sum of the digits in even positions is 0 or a multiple of 11.

A number is divisible by 3 if the sum of its digits is divisible by 3.

For a number to be divisible by 11, the difference between the sum of the digits in odd positions and the sum of the digits in even positions must be 0 or divisible by 11.

A number is divisible by 4 if the number formed by its last two digits is divisible by 4.

Adding 3 to both sides gives 2x = 10, then dividing by 2 gives x = 5.

To solve for x, add 9 to both sides and then divide by 3: 3x = 9, thus x = 3.

Solving the inequality gives 3x < 9, thus x < 3.

Prime numbers are defined as having exactly two distinct positive divisors: 1 and the number itself.

The first multiple of any number is indeed the number itself, while the other statements are false.

In base-4, valid digits are 0, 1, 2, and 3. Therefore, 123 is valid, while 234, 345, and 456 contain digits not allowed in base-4.

A number is divisible by 10 if it ends in 0.

All listed methods are valid techniques for solving systems of linear equations.

All listed methods are valid for solving systems of linear equations.

In base 8, 15 is represented as '17' (1*8 + 7).

Spherical geometry is an example of non-Euclidean geometry, where the usual rules of Euclidean geometry do not apply.

The equation y = x^2 - 4 is non-linear because it involves a variable raised to a power greater than one.

√2 is an irrational number because it cannot be expressed as a fraction of two integers.

Since 1000 is 10^3, log_10(1000) equals 3.

A Fibonacci sequence cannot be expressed as a linear function; it is defined recursively.

In a geometric progression, the terms are numeric and follow a specific ratio; thus, non-numeric terms do not fit the definition.

In a geometric sequence, the ratio between consecutive terms is constant, not the difference.

In a geometric series, the ratio between consecutive terms is constant, not the difference.

A regular polygon is defined as a polygon with all sides and angles equal, and it cannot be concave; it must be convex.

Multiples can be both odd and even; hence, they are not always odd.

The graph of a quadratic function is a parabola, not a straight line.

The factors of 60 are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60. 7 is not among them.

A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. 9 is not prime as it can be divided by 3.