Due to the difficulty in having everyone take the quiz this past Wednesday, there will be a RE-QUIZ (or first quiz for a few of you) on Tuesday, Feb 21st. EVERYONE should be checking in on the blog this weekend to prepare for the quiz. POST YOUR QUESTIONS HERE!!!
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= Sorry about the poor handwriting or rough sound quality... but:
= Question 2 " " " " "
= Question 3 " " " " "
= Question 7 " " " " "
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= Please let me know if this helped you!
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ALSO, you should be pre-reading section 6-5 "Graphing Linear Inequalities" because we will be working JOINTLY on Section 6-5 & 6-6 on Weds immediately after the BRIEF QUIZ.
I would love to get an INDIVIDUAL email from each and every one of you, in an attempt to develop an individual improvement plan. I know that many of you would like to improve your grade, I would like to improve your algebraic understanding... it just so happens that our goals match up nicely!
Please tell/text/facebook your alge-buddies about this blog post... it's a long time between classes and very few of us are in position to make it an "algbra-free" weekend.
Besides all that, ENJOY YOUR WEEKEND!!
Mr. C.
Mr. C we have seemed to have skipped over section 6-4 with breakeven points and viable/constraint problems as well as the current/wind problems. Is any of this going to be on the make up even though it wasn't taught to us?
ReplyDeleteI agree with you. As a class, we are having enough trouble with the subset of learning we have focused on... no vocab like viable/constraint or current and wind problems will be on the quiz/re-quiz... although those really shouldn't be that much of a stretch.
ReplyDeleteIf you focus on Problem Sets 6A,6B,6C,6D you should be in good shape.
number 16 on problem set 6c confused me could someone clarify
ReplyDeleteReally, you did 1-15 and you can't offer a "start" for this one. I almost have trouble believing that. AND, this has been on the blog for 24 hours plus and no one else can answer it?? Oy vey!!
DeletePS-6C #16)
7x − 2y =−21
−8x − 5y = 24
Ok, the equations are in the same form (Standard), so we simply need to "match" one pair of coefficients, right?
I prefer to match "opposite" coefficients, that way when we combine the equations we're always ADDING.
So, let's multiply the 1st by 5 and the 2nd by -2, yielding:
35x − 10y = −105
16x + 10y = -48
Add 'em and you get:
51x = -153
x = -3
Substitute back into the (original) 1st equation:
7x − 2y = −21
7(-3) - 2y = -21 (sub the -3 for x)
-21 - 2y = -21 (Add 21 tbs)
-2y = 0 (divide bs by -2)
y = 0
Substitute back into the (original) 2nd equation:
−8x − 5y = 24
-8(-3) - 5y = 24 (sub -3 for x)
24 - 5y = 24 (subt 24 fbs)
-5y = 0 (divide bs by -5)
y = 0
Yup, our solution is ( -3, 0)
Ca-peesh??
But will they be on the test at all? Do i need to know them for this retest?
ReplyDeleteIf this is the same person that asked about viable/constraint and the current/wind problems, I'm not sure if you are having more trouble with math or reading comprehension. Please re-read my response above.
DeleteOn the quiz on Thursday I was having a problem on question 9 whcih was about the stocks and insurance. I wasn't sure how to set up the system of equations for the problem that would make sense. Could you possibly show me how to solve that problem? That woould be great. Thanks!!
ReplyDeleteI'm hoping to do a video on this problem... but I'll try a written response.
ReplyDeletePeter invested a total of $4500 in insurance and stocks. He paid $350 more in insurance than stocks. How much did he invest in each?
You were asked to define variables, set up a system of equations, THEN solve.
Many of you did not define the variables. Some of you said:
i=insurance
s=stocks
AAAAHHHHHHHHHHHHHHHHHHHHHHH!!!!! The ultimate no-no!!
Here is what you should have done.
i is the amount of money invested in insurance
s is the amount of money invested in stocks
NOW, THAT'S DEFINITION OF VARIABLES WORTH THE PRICE OF A STAMP!!
Now, we just have to look for the RELATIONSHIPS.
1) The sum of the two investments is 4500 AND
2) The amount of money in insurance is 350 more than in the amount in stocks.
These two relationships translate into Algebra with this system.
i + s = 4500
i = s + 350
Now we gotsk ourselves an EASY SUBSTITUTION, since we have an easy to use "i=" equation.
i + s = 4500 (next, we'll substitute 's+350' for 'i')
(s + 350) + s = 4500 (now, combine like terms)
2s + 350 = 4500 (now subtract 350 fbs)
2s = 4150 (duh, divide by 2)
s = 2075
Well-zers, since the amount invested in stocks = 2,075 the amount invested in insurance must be 2,075 + 350 or $2,425.
To answer the question succinctly:
Peter invested $2,425 in insurance and $2,075 in stocks.
Capeesh??
i don't understand why you got rid of the 'i'. can you explain it to me?
DeleteIn our "pitiful little world" where the information from the problem is ALL that we know...
Delete$350 plus the amount of money invested in stocks is equal to the amount of money invested in insurance... so:
i = s + 350
... this sentence means that anywhere else in our world where we see 'i', we can replace it (i.e. substitute) with 's+350'....
Where else do we see an i? In the other relationship/equation, of course.
So, instead of writing:
i + s = 4500
we can write:
(s+350) + s = 4500
The advantage? We now have an equation in one variable that cna be solved for a specific x.
Did this help?... lmk...
ohhhhh yes it did. it finally hit me!! thanks!
DeleteThanks Mr C. for explaining problem 9! It really makes sense now! I think I'm having a DUH! moment!! Also the video you put up really helped me. Is it possible if you could put problem number 2 up? I want to see what I did wrong! Anyway thanx!!!
ReplyDelete#2 is posted up top in the blog post heading... enjoy!
DeleteI had trouble on #9 too,that explanation helped. Thanks Mr. C.
ReplyDeletei need help with problem set B problem 3a. i feel like the answer i got was wrong
ReplyDeletewhat was your solution?
Delete(34/-11, -79/33)
Delete2x + 3y = −1
Delete5x − 2y = −12
Well, we survey the situation (aka the "linear system") and we see that both equations are in STANDARD FORM, so that's a good thing. We need to match a pair of coefficients "vertically" to be equal or opposite. I prefer opposite because then we can ADD the equations, which (to me) is less prone to error than subtracting.
If we multiply the first by 2 and the second by 3, mission accomplished!! The new system is:
4x + 6y = −2
15x − 6y = −36
Let's add 'em together to get a new equation...
19x = -38
x = -2
Now, we substitute x=-2 into both of the orignal equations to make sure we get the same 'y'...
I'm gonna let you do that and report back with a solution... expressed in the form of an ordered pair... can you tell me why the solution is an ordered pair?
(-2,1)
DeleteI see my mistake
i didn't like your answer... do you see where you went wrong?
ReplyDeletethanks mr.c for my earlier question but i did the re-quiz you sent and i got stuck on number 9 could you help
ReplyDeletenever mind i see that the question was already asked and answered by someone else
ReplyDeleteI was also confused on #9 on the quiz because i didn't set up the right system. But that explanation helped a lot! Thanks Mr. C.
ReplyDeleteI WILL NOT BE AVAILABLE FOR ANY LIVE SESSION TODAY. I will check back for questions later. I'm hoping that if you know the answer to a question, you will choose to answer it!! Maybe you can explain it better than me??!!
ReplyDeleteWhen is the web thing going to happen?
ReplyDeleteI made it onto the live chat room!
ReplyDeleteI did figure out the answer to 9 on the quiz but i hope i remembered to define the variables that well!
Thank you for the videos Mr Chamberlain I too got that DUHH moment. All in all the videos were very helpful!
ReplyDelete-Amanda
I was really hoping for an AH-HAH moment... we have enough DUH's... thank you very much!
Deletecan you please explain number 9 on the quiz
ReplyDelete-katie
Its already up there^^
DeleteThe videos were great thanks
ReplyDeleteIs #21 on the 6-5 hw a direct variation problem?
ReplyDeletefor number 4, a on set 6f what was the third equation. i got x< or = to 250 and Y< or = to 200 but the third has cofused me.does it have something to do with the home school assosiation
ReplyDelete