Read this article, which gives examples of squaring binomials and the general formulas that always work for them. Example 1 shows how to use the formula. Note the definitions of sum and difference, which are used when multiplying one addition binomial and one subtraction binomial. Example 2 shows how to use this definition.
After you read, complete questions 1 through 5 and 14 through 18 in the practice set and check your answers.