The homework help thread...(SERIOUS)

[Cell-Tech]

grade 11 U Math

solve 5k - 8 < 7 + 2k

You can treat the inequality sign as an equal sign almost always. The only time I can think of where you can't is when you multiply or divide negative numbers.

5k - 8 < 7+2k

add 8 to both sides:

5k < 15 + 2k

subtract 2k from both sides:

3k < 15

divide both sides by 3:

k < 5

[Toronto_BBer]

another chem question:

Ethanethiol, C2H5SH, is a very smelly compound that is added to natural gas so that gas leaks can be detected easily. When the natural gas is burned, the etahnethiol undergoes combustion as well:

2 C2H5SH + 9 O2 ----> 4 CO2 + 6 H20 + 2 SO2

a) Calculate the volume at SATP of each gas produced when 1.00g of ethanethiol is burned.

I don't need the volume for all gases, I'd just like for someone to do one of the volumes for one of the gases, so I get the idea on how to do it. Thanks.

[boomer913]

http://thebrocabularylist.blogspot.com/

[jimmybody]

Algebra 2A Graphing system of equations

They give me something like


{x + 2y = -7}
{2x - 3y = 0} (Theres only one bracket btw)

So the directions says: Solve each system by graphing

So apparently i have to find the coordinates for the second step and identify them for the other sections. I understand those.

Problem: Idk how to graph it. Am i suppose to plug in 0 to solve for X and y for both equations? or distribute the first equations so that it can be negative to subract the second equation to = 1? Ive been stuck on this for awhile and im not getting anywhere.

[Cell-Tech]

Algebra 2A Graphing system of equations

They give me something like


{x + 2y = -7}
{2x - 3y = 0} (Theres only one bracket btw)

So the directions says: Solve each system by graphing

So apparently i have to find the coordinates for the second step and identify them for the other sections. I understand those.

Problem: Idk how to graph it. Am i suppose to plug in 0 to solve for X and y for both equations? or distribute the first equations so that it can be negative to subract the second equation to = 1? Ive been stuck on this for awhile and im not getting anywhere.

put them in y = mx +b form.

x + 2y = -7 ---> y = -.5x -3.5
2x - 3y = 0 ---> y = (2/3)x + 0

Graph the two lines and the point where they intersect is the answer.

[Kurd4evah]

school is over aint it?
why is this still up here....

[jimmybody]

school is over aint it?
why is this still up here....

summer school

[Kurd4evah]

summer school

oh okay, so this is going to stay for ever....

[SamParryy]

Biology
5 (specific) examples of plant pollination (not asexual) diagrams etc. so e.g orchids what adaptations they've made to help them get pollinated, then the pollinator and info on their adaptations. I've been looking for hours and can't find anything

[WelshBeats]

Hey guys, I'm doing a Mathematics degree so, hit me up

[psai]

another chem question:

Ethanethiol, C2H5SH, is a very smelly compound that is added to natural gas so that gas leaks can be detected easily. When the natural gas is burned, the etahnethiol undergoes combustion as well:

2 C2H5SH + 9 O2 ----> 4 CO2 + 6 H20 + 2 SO2

a) Calculate the volume at SATP of each gas produced when 1.00g of ethanethiol is burned.

I don't need the volume for all gases, I'd just like for someone to do one of the volumes for one of the gases, so I get the idea on how to do it. Thanks.

Calculate moles of ethanethiol burned (1.00g divided by molar mass of ethanethiol)
Then, multiply it by 4.5 (molar ratio of ethanethiol to O2 is 2:9), giving you the number of moles of oxygen used.
Next, multiply the number of moles of oxygen used by 22.4 (assuming that the gases used are ideal gases), and this gives you the volume of oxygen in liters.

[MadArabianBro]

inn

[SERLY]

well!!!!come on!!

[Toronto_BBer]

English Essay question:

I need help on deciding which Hamlet essay topic I should choose. The topics are:

1. Hamlet's story can be thought of as two simultaneous journeys: a physical outer journey and an intellectual and spiritual inner journey. Describe the development of Hamlet's chaaracter in this play in terms of these two journeys.

2. Identify one or more characters in this play that could be said to be Hamlet's foils and describe their relationships to the main character.

3. Discuss the importance of appearance vs reality in Hamlet.

Which topic would you guys think would give the most interesting thesis statement; with many ideas to support my body paragraphs. Thanks.

[Albo2468]

AP Calc Summer work

http://i.imgur.com/3mkPo.jpg

Due tomorrow, started today. (or I guess yesterday, I'm around problem 20 of 51, I'll manage. The main thing is to get the right answer, because this is treated as a test.

Can you guys help me out on numbers: 1, 2, 11, 12, 13(can you show work for this one, because I get to a certain point and idk where to go from there), 16, WTF IS 17?, and 18 (I'll keep adding to this list, because ****s real. Thanks guys, measly reps if you want them for helping me out, or at least advice.

[embulldogs99]

AP Calc Summer work

http://i.imgur.com/3mkPo.jpg

Due tomorrow, started today. (or I guess yesterday, I'm around problem 20 of 51, I'll manage. The main thing is to get the right answer, because this is treated as a test.

Can you guys help me out on numbers: 1, 2, 11, 12, 13(can you show work for this one, because I get to a certain point and idk where to go from there), 16, WTF IS 17?, and 18 (I'll keep adding to this list, because ****s real. Thanks guys, measly reps if you want them for helping me out, or at least advice.

factoring is all about what does each have in common? so heres numbero uno.

21x^4-9x^3+15x^2
they have 3x^2 in common so take it out
3x^2(7x^2-3x+5)
then try to factor the stuff inside the ()
in this case it does not factor (it would if it was -5 though) so you are just left with
3x^2(7x^2-3x+5)

2 is similar idea.

11 and 12 are same idea so ill show 11.

125x^3-27
for this one i define each as a variable. lets say 5x is now p and 3 is q. (notice p^3 is 125x^3 and q^3 is 27)
p^3-q^3= (p - q)(p² + pq + q²).
then plug back in and u have ur answer.

13 is a bit different.
x^3-3x^2-4x+12
i forget the math term for it but i call it factoring by grouping. u can only do it when there is 4 terms and they are going down in power like this. but heres what to do.
(x^3-3x^2)+(-4x+12)
factor each group
x^2(x-3)-4x(x-3)
notice when u did this the stuff inside the () are the same. this means it worked and u can use this meathod. then all u do is this factor using the same idea we did in 11- find what they have in common-
(x^2-4x)(x-3)
then u can keep going to->
x(x-4)(x-3)
bam!

16
9x^3-9
take out what have in common
9(x^3-1)
use the same idea we used in 11
x=p
1=q
p^3-q^3= (p - q)(p² + pq + q²)
then plug in
dont forget to put that 9 out front. cant forget about him.

17- no idea good luck. and i got a 5 on my ap calc. never seen that before. might be able to do it but i couldnt type it on a forum like this.
18 same deal. sorry

[CUguy2014]

Hey guys, I'm doing a Mathematics degree so, hit me up

Have fun...
























being a teacher

[asianmanlet]

AP Calc Summer work

http://i.imgur.com/3mkPo.jpg

Due tomorrow, started today. (or I guess yesterday, I'm around problem 20 of 51, I'll manage. The main thing is to get the right answer, because this is treated as a test.

Can you guys help me out on numbers: 1, 2, 11, 12, 13(can you show work for this one, because I get to a certain point and idk where to go from there), 16, WTF IS 17?, and 18 (I'll keep adding to this list, because ****s real. Thanks guys, measly reps if you want them for helping me out, or at least advice.

lol might be a bit late, but this is what I think 17 could be:

2x^3 - 8a^2x - 20x^2 + 50x
= 2x(x^2 - 4a^2 - 10x + 25) (factor out 2x)
= 2x(x^2 - 10x + 25 - 4a^2) (re-arrange for a perfect square trinomial)
= 2x[(x-5)^2 - 4a^2]
= 2x[(x-5) + 2a][(x-5) - 2a] (difference of squares)

I'm pretty sure that's as far as you can go.

18:
64b^2x - 81y - 81x + 64b^2y
= 64b^2x + 64b^2y - 81x - 81y (group the 64's and 81's together)
= 64b^2(x+y) - 81(x+y) (partial factoring)
= (64b^2 - 81)(x+y) (don't know what this is called but it probably has a name)
= (8b - 9)(8b + 9)(x+y) (difference of squares)

lol being asian is good for something I guess. PM if you need any more clarification.

[LykAg6]

find the exact value of cos 240. the answer is -1/2. Just want to know how u get it...

[Fil93]

math : calculus

Y=f '(x) with points (0:2) (-1:0) (5:0)

(a) what is the gradient of the tangent to the graph of f(x) at x=0

(b) for which value of x will there be a tangent to the curve of f which will be parallel to the tangent in (a)

(c) for which values of x will f(x) be decreasing?

(d) write down the x-coordinates of the turning points of f and state whether they are local maximum or minimum turning points

(e)If it is futher given that the x-intercept of the graph of f are (-2:0) (2:0) and (7:0) scetch the graph of f

[Fil93]

find the exact value of cos 240. the answer is -1/2. Just want to know how u get it...

cos(240) = cos(180 + 60) = -cos(60) = -1/2

proof : the reason for this is because cos=x/r and cos(240) is in the 3rd quadrant where x values are negitive so if x=-1 then r=-1/cos(60) therefore r=2

[LykAg6]

nice, i thought to work it out its like, cos 240= -cos 30 because that goes to 270..

[Fil93]

nice, i thought to work it out its like, cos 240= -cos 30 because that goes to 270..

Dont use 270, its pointless. use 90, 180 and 360

[LykAg6]

:O pointless, any logic to it?

[Nudieaesthetics]

(chemistry) Hey brahs I had to complete a basic neutralisation experiment; Vinegar(ethanoic acid) + Baking soda (Sodium Hydrogen Carbonate) yet I had to complete the reaction at different temperatures and record how the rate of reaction was affected, long story short I can't find any baking soda and my friend told me that the due date is earlier than the one on my assessment sheet and I can't find any websites describing the exact pattern with this reaction and altered temp, was wondering if one of you brahs had some experience with this or know where I can find some stats online.

[youngzealot]

Yo, anyone who can answer these gets reps for life:

a/3* divided by a/2 = ?
xy/5 divided by 2x/y = ?

Factorise the following: 6d + 12
y^2 - 7y
-3k-15

Thanks brahs

[FatAli]

Yo, anyone who can answer these gets reps for life:

a/3* divided by a/2 = ?
xy/5 divided by 2x/y = ?

Factorise the following: 6d + 12
y^2 - 7y
-3k-15

Thanks brahs

The first one would turn to a/3 multipled by 2/a which would be 2a/3a which equals 2/3.

Factoring is quite simple... take what is the same from every part of the example.

1) 6d + 12 -> 3 is common to each part. It would then be 3(2d+4).
2) y^2 - 7y -> y(y-7)
3) -3k-5 --> -3(k+5)

[youngzealot]

The first one would turn to a/3 multipled by 2/a which would be 2a/3a which equals 2/3.

Factoring is quite simple... take what is the same from every part of the example.

1) 6d + 12 -> 3 is common to each part. It would then be 3(2d+4).
2) y^2 - 7y -> y(y-7)
3) -3k-5 --> -3(k+5)

thankyou so much man sorry about my reps being measly to you but*I will on every r/c .

[UngeneticAzn]

(chemistry) Hey brahs I had to complete a basic neutralisation experiment; Vinegar(ethanoic acid) + Baking soda (Sodium Hydrogen Carbonate) yet I had to complete the reaction at different temperatures and record how the rate of reaction was affected, long story short I can't find any baking soda and my friend told me that the due date is earlier than the one on my assessment sheet and I can't find any websites describing the exact pattern with this reaction and altered temp, was wondering if one of you brahs had some experience with this or know where I can find some stats online.

A general rule is that with every 10 degrees Celsius increase, the rate of the reaction will double. You could probably BS something with that.

[UngeneticAzn]

:O pointless, any logic to it?

You should only be using 0, 180 or 360 because that's the only way to find the complimentary angle. If you use 90 or 270 you're gonna get the wrong answer. Also don't forgot to change the sign depending on what quadrant the angle is in.