Page 1 of 1 [ 2 posts ]
 Print view Previous topic | Next topic
Author Message
 Post subject: Algebra (Vol. IV), Question #94.Posted: Sat Oct 30, 2010 12:32 pm

Joined: Thu Jul 01, 2010 12:05 am
Posts: 35
This question asks the following: "For all numbers q and r, the operation ☼ is defined by q ☼ r = (q + 3)(r - 2). If 1 ☼ z = -8, z is equal to which of the following?

The correct answer is D, which has z = 0. I'm confused about the use of words "the operation ☼ is defined by(...)." I imaged operation ☼ as the following: f(☼) = q ☼ r = (q + 3)(r - 2). Since we had 1 ☼ z = -8, I rearranged this equation and deduced that we're looking for z = -8/☼. In other words, I had to solve for the following to obtain z: -8/(q + 3)(r - 2). I was stuck at this point. After looking at the solution, I am still uncertain about the term "the use of operation ☼."

Top

 Post subject: Re: Algebra (Vol. IV), Question #94.Posted: Mon Nov 01, 2010 5:00 am

Joined: Thu Oct 21, 2010 5:19 am
Posts: 16
This is my understanding,

I thought that "the operation ☼ is defined by(...)." just gave the condition of the question.

Look at this question in this way.

q r = (q + 3)(r - 2).
1 z = -8

compare the left of the two equations.(notice the same colore signals)

It is clear that q=1, r=z, and (q + 3)(r - 2)=-8.

then put q=1, r=z into (q + 3)(r - 2)=-8

(1+ 3)(z - 2)=-8

thus z=0

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 2 posts ]

 All times are UTC - 8 hours [ DST ]

#### Who is online

Users browsing this forum: No registered users and 1 guest

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

 Search for: