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  1. sergey_le

    Common ion in solution

    Summary:: finding concetrations [Thread moved from the technical forums] i did a lab experiment and i'm a little confused about what i should do. i got a solution of CaCl(2) 1.5 gr and Ca(OH)2 5gr in 100ml that i prepared 2 weeks ahead . after filttering the solution i got a saturated...
  2. sergey_le

    Chemical kinetics lab question

    last week i did a chemistry lab. i mixed NaOH 0.03M with equal part of methyl violet and mesured aborbance in a spectrophotometer. then i did the same thing with a 0.05M and methyl violet i did today the graphs and got the k' =-0.1647 for the first solution and k'=-0.4022 for the second...
  3. sergey_le

    Calculations involving acids and bases

    Summary:: finding ml of two solutions by the final pH i have a NaOAc 0.1M and HOAc 0.1M , together the volume of the solutions is 20ml and the pH is 4. I need to find the volume of each solution. I've tried to solve it for hours with no successes. i found the H+ concentration (-log(h)=4 ), it...
  4. sergey_le

    The most likely structure from combinations of these atoms

    an element (we will call it X) got a cofiguration of 1##s^2##2##s^2##2##p^6##3##s^2##s##p^3## what molecule is moste likely to happend between this element and Mg? 1.MgX 2.##Mg_2##X 3.Mg##X_2## 4.##Mg_3## ##X_2## how do i do it?with lewis structure?just check what structure makes the most...
  5. sergey_le

    Prove that this function is nonnegative

    What I wanted to do was set f(x)=##x^2##/2 - xcosx+sinx And show that f(x)>0. f'(x)=x(1+sinx) First I wanted to prove that f(x)<0 in the interval (0,∞) 0≤1+sinx≤2 And thus for all x> 0 f'(x)≥0 and therefore f(x)≥f(0)=0 And it doesn't help me much because I need to f(x)>0
  6. sergey_le

    Let a_n be sequence so that a_n+1-a_n>-1 and |a_n|>2 for all n.

    I need help only in section 3 I have some kind of solution but I'm not sure because it seems too short and too simple. We showed in section 1 that an> 0 per n. it Given that a_n + 1 <0 and a_n+1<\frac a_n a_1 In addition therefore a_1 <0 is warranted
  7. sergey_le

    Proving inequalities for these Sequences

    I need help only in section 3 I have some kind of solution but I'm not sure because it seems too short and too simple. We showed in section 1 that an> 0 per n. Given that an + 1 <0 and an + 1 = an / a1 therefore a1 <0 is warranted
  8. sergey_le

    Rolle's theorem

    It all makes sense to me, but I don't know how to formalize it nicely. I wanted to divide it into two cases. First case where f is fixed in the segment. And a second case where f is not fixed in the segment. But I don't know how to prove it for the case where f i is not fixed
  9. sergey_le

    Let function ƒ be Differentiable

    What I've tried is: I have defined a function g(x)=f(x)-x^2/2. g Differentiable in the interval [0,1] As a difference of function in the interval. so -x≤g'(x)≤1-x for all x∈[0,1] than -1≤g'(x)≤0 or 0≤g'(x)≤1 . Then use the Intermediate value theorem . The problem is I am not given that f' is...
  10. sergey_le

    Prove that f(x)=c has a solution

    I'm not sure that inff(0,∞)=0 can help But that was the first section of the question so I thought to point it out anyway. I'm not sure what I'm supposed to do or what I'm supposed to show. I was thinking of using the right environment of 0 where f aims for infinity but I don't know how it...
  11. sergey_le

    Uniformly continuous part 2

    The first thing I thought about doing was to prove that f is continuous using the Heine–Cantor theorem proof. But I do not know at all whether it is possible to prove with the data that I have continuous. I would love to get help. Thanks
  12. sergey_le

    Uniform continuity

    There are two parts to the question Let's start with part :) I understand the definition of Uniform continuity And I think I'm in the right direction for the solution but I'm not sure of the formal wording. So be it ε>0 Given that yn limyn-xn=0 so For all ε>0 , ∃N∈ℕ so that For all N<n ...
  13. sergey_le

    Another minimum point

    Here's what I tried to do: f Continuous function at R, x1 local minimum point of f, x2 local maximum point of f. Existing f(x1)>f(x2). Let's look at the interval [x1,x2]⊆ℝ . f is continuous in R and therefore continuous in its partial segment. Therefore f continuous in [x1,x2]. Therefore, there...
  14. sergey_le

    A question not related to Calculus

    Homework Statement:: I don't understand what I need to write here Homework Equations:: I don't understand what I need to write here hello :) I recently posted a post and it was deleted because I did not comply with forum rules. Now I'm trying to figure out what to do right. So I want to ask...
  15. sergey_le

    Multi-Choice Question: Differentiable function

    be f Differentiable function In section [0,1] and f(0)=0, f(1)=1. so: a. f A monotonous function arises in section [0,1]. b. There is a point c∈[0,1] so that f'(c)=1. c. There is a point c∈(0,1) where f has Local max. I have to choose one correct answer.
  16. sergey_le

    Uniform continuity

    I came across the following question: If g and f are uniform continuity functions In section I, then f + g uniform continuity In section I. I was able to prove it with the help Triangle Inequality . But I thought what would happen if they asked the same question for f-g I'm sorry if my...
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