In a quadratic equation written as ax^2 + bx + c, the term that carries x squared is the one with x^2. This is the squared variable part, since x is multiplied by itself. The bx term has x to the first power (the linear term), and c is the constant term (a plain number). The x^2 term, multiplied by the coefficient a, is what shapes the parabola.

Integers are all whole numbers, including negatives, zero, and positives. This means numbers like -7, 0, and 12 are integers, and they have no fractional part. Natural numbers are the counting numbers and typically start at 1 (sometimes 0), so they don’t include negative numbers. Irrational numbers cannot be written as a fraction of integers, so they aren’t integers. Rational numbers are numbers that can be expressed as a fraction p/q with integers p and q ≠ 0; this set includes integers as a special case (every integer is a fraction with denominator 1), but the idea described by the term “integers” is the set of numbers with no fractional part. Therefore, the set that matches the description is the integers.

The multiplicative inverse of a nonzero number n is the number that you multiply n by to get 1. That number is 1/n, so n × (1/n) = 1 for every nonzero n. This works whether n is positive or negative, because the n and 1/n cancel to give 1. The other expressions don’t define the reciprocal: n × n = 1 would only hold when n is 1 or -1; (1/n) × (1/n) = 1 would require 1/n^2 = 1, again only for n = ±1; and n × 0 = 0 uses zero, not the inverse.

Think in terms of how miles convert to feet. A mile is 1760 yards, and each yard has 3 feet. So multiply 1760 by 3 to get 5280 feet. That’s why the option stating 5280 feet is the exact conversion. The other numbers would represent half a mile (2640), a little over a mile (6000), or about a kilometer (3200), which do not match the precise mile-to-feet relationship.