Can you do grade 9 math?

[Darth Wong]

Sorry I've been absent from the board lately, but I've been extremely busy in real-life. On the upside, I finished my taxes and the government owes me a refund. Anyway, can you do grade 9 math? Just for fun, the following questions are taken from one of my son's grade 9 math tests.

Question 1: Simplify the following 3 expressions:

a)

(7x2 - 2x + 9) - (2x2 - 7x - 16) + (4x2 + 3x - 6)

b)

(mn0p)(2m3n6p4)(3m2n1p3)2

c)

27wx4y3z

  

9xy3z4

Question 2: Factor the following 4 expressions:

a)

8x2y6z + 4x3y4z

b)

y2 - 6y + 8

c)

x4 - 16

d)

2x2yz - 4xyz + 2yz

Question 3: Simplify the following 2 expressions:

a)

54x2y3 + 36x2y + 18xy4

  

6xy

b)

(x2 + 3x)(2x2 - 5x + 3) - (2x + 3)(2x - 3)

Question 4: Solve for x in the following 4 equations:

a)

x + 9 = 81

b)

x/15 = 6/135

c)

3(x + 1) - 4 = -28

d)

(3x + 2)/6 = 1 - (x + 1)/3

Question 5: Mr. Baxter surveyed 200 students. He found that 156 of them said Math was their favourite subject. If this sample is representative of the entire school, then how many of the school's 1257 students have math as their favourite subject?

Question 6: Tony loves Smarties. He went to the candy store and bought a huge bag of 2500 Smarties, and he has been eating them at a rate of 37 Smarties per minute. Therefore, the number of Smarties in his bag at any moment can be calculated using the formula:

N = 2500 - 37t

Where N is the number of Smarties and t is the number of minutes which have elapsed since Tony started eating his Smarties.

a) How many Smarties will Tony have left after one hour?
b) Rearrange the formula to isolate t
c) How many hours will it take for Tony to finish the bag? Round to 2 decimal places.

Remember, these questions are taken from a grade 9 test (which is coincidentally around the minimum age to be on this board). We're not talking about advanced math here. I'm posting this just so people have a reminder of what level should be considered "basic". It's been a while since most of us were in grade 9, and we may not have a good recollection of what kids are expected to know at that age. Also keep in mind that this is just a test from the middle of the year, not a complete final exam or anything.

I hope there are no adults here who look at this in confusion. If you have kids someday, you will have to help them with their homework, and grade 9 is way too early to say "you've moved beyond me".

[The Grim Squeaker]

I can do all of those very easily, although knowing myself i'd probably make a calculation/rote error in (mn0p)(2m3n6p4)(3m2n1p3)^2, but it's all very easy.

[Darth Wong]

it's all very easy.

Well of course it is; it's grade 9. It's just that the question occasionally comes up of whether it's OK to call someone a fucking retard if he can't do a simple algebraic rearrangement, and this is a reminder of what a 14 year old kid is expected to know. Someone who has actually graduated high school should be able to do this very easily. We do accept that people slide back a bit if they haven't done things for a while, but sliding all the way back to middle school is a bit much.

[Liberty]

Yay! I'm not a major math person, (though not for lack of ability, rather for lack of desire), but those problems are all a piece of cake. It's been over four years since I've taken a math class or done any math to speak of, but it's good to know I haven't lost the math I learned in high school. Or at least, 9th grade.

[Argosh]

Anyway, can you do grade 9 math?

Yeah, it could be fun even. I don't believe I just said that math is fun.

[Zac Naloen]

I can do 4,5 and 6 without breaking a sweat but i'll hold my hands up I've forgotten the methodology for the first three and I'd need to go find a maths text book to remind myself what the process to solve it is.


*edit*

Actually simplifying just came back to me just by reading the equation through closer, still can't remember how to factor though.

[Serafina]

I am honestly not sure wether i would get the right solution for the simplifications. I propably would, but i can't tell until i tried.
The others are a cakewalk.

[AMT]

Waiting to see if everyone saying it's easy will actually provide, you know, answers rather than the me-tooing that seems to occur.

As for myself, this just goes to how it's a good thing I'm taking college algebra this summer as I start on my second degree. It's been way too long since I've hit the books...
Simplifications I think I'm doing right, tho it's been so long I've forgotten like half the rules since I just don't use this stuff.
The regular solving for X tho, is easy enough for me. Factoring... is painful.

Sometimes I wonder if university level courses focus people so much that they actually lose the general knowledge they had when they were younger due to that focus forcing everything on the narrow path rather than the broad, since I could easily do all this stuff back in high school.

Here's some of what I have so far. If I'm wrong, be gentle. It's been a loooong time.
Spoiler

(7x^2-2x+9)-(2x^2-7x-16)-(4x^2+3x+6) simplifies to x^2-6x-19

x+9=81
x=72

x/15=6/135
x/15=0.044444
x=0.6, or (2/3)

3x+3-4=-28
3x-4=25
3x=29
x=-9 and 2/3

(3x+2)/6=1-(x+1)/3
.5x+(1/3)=1-(1/3)x+(1/3)
(5/6)x+(1/3)=1+(1/3)
(5/6)x=1
x= 1 (2/3)

[D.Turtle]

No using calculators!

Some corrections for AMT (in the spoiler tags):

Spoiler

(7x^2-2x+9)-(2x^2-7x-16)-(4x^2+3x+6) simplifies to x^2-6x-19
You wrote down the first question incorrectly: It is PLUS the third Parenthesis.
However, even using what you wrote down, your answer is still incorrect. It should have been x^2+2x+19 using your incorrect copy.


x/15=6/135
x/15=0.044444
x=0.6, or (2/3)
0.6 does not equal 2/3
How to do x/15=6/135 correctly:
Multiply both sides with 15 -> x=6*15/135= 6*15/(9*15)=6/9=2/3

3x+3-4=-28
3x-4=25
3x=29
x=-9 and 2/3
You missed the negative sign before the 28 in the first line. However, the rest of your calculation is correct (if you incorporate the mistake).

(3x+2)/6=1-(x+1)/3
.5x+(1/3)=1-(1/3)x+(1/3)
(5/6)x+(1/3)=1+(1/3)
(5/6)x=1
x= 1 (2/3)
Your last step is wrong. From (5/6)x=1 you get x= 6/5

Actually simplifying just came back to me just by reading the equation through closer, still can't remember how to factor though.

The goal of factoring is to have a multiplication at the end. So for example, going from x²+x to x(x+1), or using the binomial theorem (is that the correct word in English?), so going from x²+2x+1 to (x+1)².

[Guardsman Bass]

Let's see-
Spoiler

A) (7x^2 - 2x + 9) - (2x^2 - 7x - 16) + (4x^2 + 3x - 6)

7x^2 - 2x + 9 - 2x^2 + 7x + 16 +4x^2 + 3x -6

9x^2 + 8x + 19

B) (mn^0p)(2m^3n^6p^4)(3m^2n^1p^3)^2

(mn^0p)(2m^3n^6p^4)(9m^4n^2p^6)

18m^8n^8p^11

[Ziggy Stardust]

When I first saw the questions I did a little double take. I don't remember doing stuff like this in math class in 9th grade. I'm sure I did, but man, it has been a while. After my initial shock, though, it all came back pretty quickly ...
Spoiler

1a. 9x2 + 8x + 19
1b. 18m8n8p11
1c. 3wx3 / z3

2a. 4x2y4z(2y2 + x)
2b. (2 - y)(4 - y)
2c. (4 + x2)(2 + x)(-2 + x)
2d. 2yz(x2 - 2x + 1)

4a. x = 72
4b. x = 2/3
4c. x = -3
4d. x = -2/5

I didn't do all of them, because I don't have the time at the moment. But I am pretty sure I got the ones I did fine.

[AMT]

Schooling me.

Ah, yes, I see now.
This summer is going to be fun for me.

Well.. good for me, but not fun.

[Colonel Olrik]

c) factor x^4 - 16
Spoiler

x^4 - 16 = (x+2)(x-2)(x+2i)(x-2i)

My kid will love me.

[Venator]

Oddly enough, this came back to me very easily (around seven years ago now), but having just finished third year, first-year calculus is pretty much gone. Is that something anyone else has experienced?

[Colonel Olrik]

Sorry I've been absent from the board lately, but I've been extremely busy in real-life. On the upside, I finished my taxes and the government owes me a refund. Anyway, can you do grade 9 math? Just for fun, the following questions are taken from one of my son's grade 9 math tests.

Some months ago I had the experience of helping a 9th grade math teacher in her thirties prepare for exams (in order to teach some other grade). Those days taught me that the average high school teacher barely can do math, and certainly doesn't fully understand how he or she is doing it.

[Colonel Olrik]

I can do all of those very easily, although knowing myself i'd probably make a calculation/rote error in (mn0p)(2m3n6p4)(3m2n1p3)^2, but it's all very easy.

Addition and multiplication are too tough for you?

[Darth Wong]

Sorry I've been absent from the board lately, but I've been extremely busy in real-life. On the upside, I finished my taxes and the government owes me a refund. Anyway, can you do grade 9 math? Just for fun, the following questions are taken from one of my son's grade 9 math tests.

Some months ago I had the experience of helping a 9th grade math teacher in her thirties prepare for exams (in order to teach some other grade). Those days taught me that the average high school teacher barely can do math, and certainly doesn't fully understand how he or she is doing it.

I learned why this is the case. Apparently, if they don't have enough teachers of a given specialization, it is considered acceptable to use a teacher who lacks that specialization. The union's bargaining contract requires that a teacher with seniority, even if totally unqualified in the subject matter, should always get such a position ahead of a new job applicant even if the new applicant is far more qualified in that area.

In short, if they have a glut of English teachers with seniority (meaning that they should let some of them go) and they have job openings in Math, they will use an English teacher to teach Math, and they will tell an aspiring and fully qualified Math teacher to go fuck off.

[Colonel Olrik]

I learned why this is the case. Apparently, if they don't have enough teachers of a given specialization, it is considered acceptable to use a teacher who lacks that specialization. The union's bargaining contract requires that a teacher with seniority, even if totally unqualified in the subject matter, should always get such a position ahead of a new job applicant even if the new applicant is far more qualified in that area.

In short, if they have a glut of English teachers with seniority (meaning that they should let some of them go) and they have job openings in Math, they will use an English teacher to teach Math, and they will tell an aspiring and fully qualified Math teacher to go fuck off.

Just something I forgot to point out, this friend of mine is a Canadian expat in Munich, teaching at the International school for the moment

[AMT]

Sorry I've been absent from the board lately, but I've been extremely busy in real-life. On the upside, I finished my taxes and the government owes me a refund. Anyway, can you do grade 9 math? Just for fun, the following questions are taken from one of my son's grade 9 math tests.

Some months ago I had the experience of helping a 9th grade math teacher in her thirties prepare for exams (in order to teach some other grade). Those days taught me that the average high school teacher barely can do math, and certainly doesn't fully understand how he or she is doing it.

I learned why this is the case. Apparently, if they don't have enough teachers of a given specialization, it is considered acceptable to use a teacher who lacks that specialization. The union's bargaining contract requires that a teacher with seniority, even if totally unqualified in the subject matter, should always get such a position ahead of a new job applicant even if the new applicant is far more qualified in that area.

In short, if they have a glut of English teachers with seniority (meaning that they should let some of them go) and they have job openings in Math, they will use an English teacher to teach Math, and they will tell an aspiring and fully qualified Math teacher to go fuck off.

That's... disturbing.
It's too bad no one has ever made a centralized distance learning program at the national level. While they might have a small lack of one-on-one attention, at the least students would have a chance to learn the stuff from someone with the right accredations.

[aerius]

I can do it, but goddamn, they must've had really shitty standards at my school since I didn't learn some of this stuff till grade 10 & 11. We didn't do factoring till grade 11 and problems such as 1 & 3 weren't covered until grade 10. No wonder I struggled like hell in grade 11, we probably didn't cover half the material we were supposed to in the lower grades.

[Highlord Laan]

Getting a piece of paper and a pencil for this. Christ, it's been so long since I've done this that I can only barely remember. Looks like I need to get a math textbook from the library and brush up, I used to be able to do this in my head with ease.

[Havok]

Well, I could probably do it when I was in 9th grade, or more accurately, 8th. Now... it looks like absolute gibberish.
My high school made the pretty big mistake of allowing us to choose our own classes when I got to 9th grade. I went straight for the Math Skills line. (That is basic addition and subtraction... literally) Then in 10th grade I took Algebra A, even though I was like a year or two ahead of that before I even got to high school, thus fulfilling my two years of required math.

In hindsight, I am completely happy with my decision.

[Aaron]

Looks like absolute gibberish to me as well. Pretty sad considering I used to be able to do antenna calculations all the time at work. Remember kids; drugs, booze and brain injuries will make you dumb!

[The Grim Squeaker]

I can do all of those very easily, although knowing myself i'd probably make a calculation/rote error in (mn0p)(2m3n6p4)(3m2n1p3)^2, but it's all very easy.

Addition and multiplication are too tough for you?

When they involve long rote/dirty work, I tend to make mistakes. I passed physics calc just fine, my problem is my inability to focus and tendancy to make stupid process mistakes.

Math is easy, order is hard. (I tend to forget something along the way with long boring work). So, yeah, I fuck up the basic/easy stuff.

[Uraniun235]

I can do 4,5 and 6 without breaking a sweat but i'll hold my hands up I've forgotten the methodology for the first three and I'd need to go find a maths text book to remind myself what the process to solve it is.

Same here; I remember being able to do it but it's been a long time since I did any math of that sort.