Multiplying polynomials is a distributive property. If you are given with two binomials and asked to multiply them, you need to apply the distributive property and multiply the terms of binomial with the terms of second binomial. To do this first take a term of first binomial and multiply it with the second complete binomial. Now take the second term of first binomial and multiply it with the second binomial adding or subtracting it from the previous result depending on the sign between the first and second terms on the first binomial. Similarly do this for the rest of the terms of the first binomial. Now add up all the like terms and simplify it to arrive at the result. This video shows how to multiply binomials using the distributive property.