A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 4 years ago
Factor Completely.
81a^2  25
anonymous
 4 years ago
Factor Completely. 81a^2  25

This Question is Closed

Compassionate
 4 years ago
Best ResponseYou've already chosen the best response.1(9a  5)(9a + 5) It is a perfect square binomial.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0how did you get that?

LifeIsADangerousGame
 4 years ago
Best ResponseYou've already chosen the best response.0In order to get factors, you have to multiply two expressions with brackets together. So, Compassionate is made the equatoin (9a  5)(9a  5) (I don't think there is a such thing as division in this case)

LifeIsADangerousGame
 4 years ago
Best ResponseYou've already chosen the best response.0Oops! I'm so sorry, that was a PLUS not a division sign! Here's the correct expression: (9a  5)(9a + 5)

Compassionate
 4 years ago
Best ResponseYou've already chosen the best response.1FACTORING IS THE REVERSE of multiplying. Skill in factoring, then, depends upon skill in multiplying: Lesson 16. As for a quadratic trinomial  2x² + 9x − 5  it will be factored as a product of binomials: (? ?)(? ?) The first term of each binomial will be the factors of 2x², and the second term will be the factors of 5. Now, how can we produce 2x²? There is only one way: 2x· x : (2x ?)(x ?) And how can we produce 5? Again, there is only one way: 1· 5. But does the 5 go with 2x  (2x 5)(x 1) or with x  (2x 1)(x 5) ? Notice: We have not yet placed any signs How shall we decide between these two possibilities? It is the combination that will correctly give the middle term, 9x : 2x² + 9x − 5. Consider the first possibility: (2x 5)(x 1) Is it possible to produce 9x by combining the outers and the inners: 2x (that is, 2x· 1) with 5x ? No, it is not. Therefore, we must eliminate that possibility and consider the other: (2x 1)(x 5) Can we produce 9x by combining 10x with 1x ? Yes  if we choose +5 and −1: (2x − 1)(x + 5) (2x − 1)(x + 5) = 2x² + 9x − 5. Skill in factoring depends on skill in multiplying  particularly in picking out the middle term Problem 1. Place the correct signs to give the middle term. a) 2x² + 7x − 15 = (2x − 3)(x + 5) b) 2x² − 7x − 15 = (2x + 3)(x − 5) c) 2x² − x − 15 = (2x + 5)(x − 3) d) 2x² − 13x + 15 = (2x − 3)(x − 5)

Compassionate
 4 years ago
Best ResponseYou've already chosen the best response.1No problem. You're just putting it in binomials, and if it can factor out again then it's correct! Let me give you can example: 81a^2  25 When factored: (9a  5)(9a + 5) This is true because if I FOIL(First, inner, outer, last.) I will get the original expression: 81a^2 + 45a  45a  25 (Notice that my 45a's can be added, but they cancel each other out.) So you're left with (81a^2  25) Which is a perfect square binomial.
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.