A function tries to define these relationsips. It tries to give the relationship a mathematical form. An equation is a mathematical way of looking at the relationship between concepts or items. These concepts or items ar represented by what are called variables.
A variable represents a concept or an item whose magnitude can be represented by a number, i.e. measured quantitatively. Variables are called variables because they vary, i.e. they can have a variety of values. Thus a variable can be considered as a quantity which assumes a variety of values in a particular problem. Many items in economics can take on different values. Mathematics usually uses letters from the end of the alphabet to represent variables. Economics however often uses the first letter of the item which varies to represent variables. Thus p is used for the variable price and q is used for the variable quantity.
An expression such as 4x3 is a variable. It can assume different values because x can assume different values. In this expression x is the variable and 4 is the coefficient of x. Coefficient means 4 works together with x. Expressions such as 4x3 which consists of a coefficient times a variable raised to a power are called monomials.
A monomial is an algebraic expression that is either a numeral, a variable, or the product of numerals and variables. (Monomial comes from the Greek word, monos, which means one.) Real numbers such as 5 which are not multiplied by a variable are also called monomials. Monomials may also have more than one variable. 4x3y2 is such an example. In this expression both x and y are variables and 4 is their coefficient.
The following are examples of monomials:
x, 4x2, -6xy2z, 7
One or more monomials can be combined by addition or subtraction to form what are called polynomials. (Polynomial comes from the Greek word, poly, which means many.) A polynomial has two or more terms i.e. two or more monomials. If there are only two terms in the polynomial, the polynomial is called a binomial.
The expression 4x3y2 - 2xy2 +3 is a polynomial with three terms.
These terms are 4x3y2, - 2xy2, and 3. The coefficients of the terms are 4, -2, and 3.
The degree of a term or monomial is the sum of the exponents of the variables. The degree of a polynomial is the degree of the term of highest degree. In the above example the degrees of the terms are 5, 3, and 0. The degree of the polynomial is 5.
Remember that variables are items which can assume different values. A function tries to explain one variable in terms of another.
Consider the above example where the amount you choose to spend depends on your salary. Here there are two variables: your salary and the amount you spend.
Independent variables are those which do not depend on other variables. Dependent variables are those which are changed by the independent variables. The change is caused by the independent variable. In our example salary is the independent variable and the amount you spend is the dependent variable.
To continue with the same example what if the amount you choose to spend depends not only on your salary but also on the income you receive from investments in the stock market. Now there are three variables: your salary and your investment income are independent variables and the amount you spend is the dependent variable.
Step-by-step explanation:
A function is a mathematical relationship in which the values of a single dependent variable are determined by the values of one or more independent variables. Function means the dependent variable is determined by the independent variable(s).
