Date: 6/13/96 at 12:36:13 From: Anonymous Subject: Expand binomial Hi! I'm from R. H. Dana and I want to ask you a question. Expand: (2x + 3)(x - 5)
Date: 6/13/96 at 21:27:6 From: Doctor Paul Subject: Re: Expand binomial Let's talk about how to do this problem in the general case and then we'll do it in your specific case. When asked to expand a problem like: (A + B)(C + D) there is a procedure to follow... Step One: Multiply A and C Step Two: Multiply A and D; Then add this to step one Step Three: Multiply B and C; Then add this to step two Step Four: Multiply B and D; Then add this to step three. You would end up with A*C + A*D + B*C + B*D Now let's do your specific case of: (2x+3)(x-5) Step One: 2x*x = 2x^2 Step Two: 2x*(-5) = -10x Now add -10x to step one: 2x^2 - 10x Step Three: 3*x = 3x Now add 3x to step two: 2x^2 - 10x + 3x Step Four: 3*(-5) = -15 Now add -15 to step three: 2x^2 - 10x + 3x - 15 Finally, simplify step four: 2x^2 - 7x - 15 -Doctor Paul, The Math Forum Check out our web site! http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.