The Official Homework Help Thread

[Mink]

Hey guys! I'm taking chemistry and I need some help!- what exactly are "exact" numbers lol and integers? If density is m/v and mass = 18.091 and volume = 6 would the density be 3 because of the volume or 3.0152 because it's limited by the mass? if someone could explain, it would be great c: (regarding significant figures I guess)

 

[Damniel]

Um I failed my Chem tests with those sig digits buy I'll try to help, to get the density you will need to decide mass by volume. The exact number means the number you got not a rounded one. I believe you use the sig digits of the number with the least amount(so 6) and use 1 digit. So your answer should be 3., sorry if I'm wrong I'm very unconfined the when it comes to this so it may also be the exact opposite and you use the greater sigs so the answer would be 3.0152.
Sorry if i didn't help

 

[radical6]

Did you try plugging in x for 4 and f(x) for 8 and then solving for a? I'll try it right now and see what I get.

This is what I did:

f(x)=a(x-1)(x-3)^2
8=a(4-1)(4-3)^2
8=a(3)(1)^2
8=a(3)(1) (remember to do 1 squared first, not 3 times 1 and then square that!)
8=3a
8/3=a

f(x)=(8/3)(x-1)(x-3)^2

Hope this answers your question!

Oh. I put the wrong numbers in, oops. This worked. Thank you!

 

[Zandy]

Hey guys! I'm taking chemistry and I need some help!- what exactly are "exact" numbers lol and integers? If density is m/v and mass = 18.091 and volume = 6 would the density be 3 because of the volume or 3.0152 because it's limited by the mass? if someone could explain, it would be great c: (regarding significant figures I guess)

The set of integers is the set of all positive/negative whole numbers. In other words, the integers are the numbers:

..., -3, -2, -1, 0, 1, 2, 3, ...

For example, 5 is an integer, -10003 is an integer, 8/4 = 2 is an integer, 4.0 is an integer, 2/3 is not an integer, and π is not an integer.

 

[Trundle]

Hey guys! I'm taking chemistry and I need some help!- what exactly are "exact" numbers lol and integers? If density is m/v and mass = 18.091 and volume = 6 would the density be 3 because of the volume or 3.0152 because it's limited by the mass? if someone could explain, it would be great c: (regarding significant figures I guess)

Sounds like you are trying to do sig digs.

Addition / Subtraction Rules: digit to the least precise of what you added / subtracted

5.012 - 3.01 = 2.00 <-- 0 preceding decimals almost always count as one sig dig per 0
3.423 + 3.2235 = 6.646 <-- 4 significant digits because the least precise number (3.423) was only 4 digits

Multiplication / Division Rules: (i have to go i'll edit later)

 

[Mao]

bump c:

 

[Mao]

Just to confirm, is magnesium or calcium more reactive? Google says calcium but my teacher says magnesium...

 

[Aestivate]

Just to confirm, is magnesium or calcium more reactive? Google says calcium but my teacher says magnesium...

I've had a couple years of, well, classes including this. Though those weren't in english and I doubt that I can explain this in English but I'll try. If a metal is more noble it reacts less easily. Metals that don't show corrosion are called noble (I don't know really, that's the direct english translation I get). Vile (??) metals show corrosion and showing corrosion
Forget this. Appears to be that 'calcium' doesn't has the same translation as I thought.

So, pure magnesium is hexagonal and therefore doesn't react easily, in fact, barely. Calcium is more reactive because it has a bigger cell structure.

Again, sorry for my lacky English explanation.

 

[Sona]

bump

 

[KarlaKGB]

So, pure magnesium is hexagonal and therefore doesn't react easily, in fact, barely. Calcium is more reactive because it has a bigger cell structure.

Again, sorry for my lacky English explanation.

wat are u talking about

the answer is calcium is more reactive. the simplest explanation is that calcium has more electrons, it has an extra electron shell compared to magnesium, therefore the outer electrons are further from the nucleus, therefore the nuclear attraction is weaker, therefore those electrons are easier to remove, therefore more reactive.

 

[Sona]

boomp

 

[DarkDesertFox]

Anyone know how they got 1.7 as the answer? I can't seem to figure it out. I posted my class notes on the left. The class number should be 7 I think. I'm not good at reading stem-leaf plots so I don't really know what numbers to divide. I thought it would be (83-76)/7, but I can't seem to get the right answer.

 

[KarlaKGB]

as ur notes say, K is the smallest whole number for 2^k greater than or equal to n

n = 12 (u have 12 pieces of data)

therefore k = 4

ur range is 83.8 - 76.9 = 6.9

divide that by 4 and u get 1.725

i assume cuz the data is only up to 1 decimal place, u quote the class length to that as well

 

[DarkDesertFox]

as ur notes say, K is the smallest whole number for 2^k greater than or equal to n

n = 12 (u have 12 pieces of data)

therefore k = 4

ur range is 83.8 - 76.9 = 6.9

divide that by 4 and u get 1.725

i assume cuz the data is only up to 1 decimal place, u quote the class length to that as well

Ahh, I see now. So n is the number of data on the stem-leaf plot. There was actually a chart in my notes I didn't notice that was part of the example that had 65 pieces of data on it. Thank you so much! This will really help me if this problem pops up on my exam.

 

[00jachna]

I'm terrible at math and I need help with solving √63 ? √7a?b?

No-one has ever explained how to do it so I have no clue! How do I go about solving this type of problem?

 

[KarlaKGB]

I'm terrible at math and I need help with solving √63 ? √7a?b?

No-one has ever explained how to do it so I have no clue! How do I go about solving this type of problem?

that doesnt even make sense, like wat are a and b

 

[DarkDesertFox]

I'm terrible at math and I need help with solving √63 ? √7a?b?

No-one has ever explained how to do it so I have no clue! How do I go about solving this type of problem?

Mathway says it's 3/ab. I have the premium membership on my portable device so here's the steps it gave me:

Hope this helps!

 

[KarlaKGB]

we dont even kno if the a and b are inside the sqrt

that mathway stuff is also unnecessarily complicated cuz its a dumb computer doing the solving

 

[Zandy]

I'm terrible at math and I need help with solving √63 ? √7a?b?

No-one has ever explained how to do it so I have no clue! How do I go about solving this type of problem?

If the question was √63 ? √(7a?b?) then the solution that DarkDesertFox gave is correct, though, KarlaKGB makes a good point in noting that you were not given what the values of "a" and "b" were, so they may be positive or negative. If a is positive and b is negative, then √63 ? √(7a?b?) is still defined and is clearly positive, however, it is not equal to 3/(ab) since then 3/(ab) is a negative number.

The most general solution would therefore be |3/(ab)|.

It's very subtle but easy to miss xP. I hope this makes sense .

 

[Farobi]

I need clarification... If I have 4x^2 and x is given as, say 3, which do I multiply first??