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  1. L

    How much sleep do we need?

    sleep is for the weak
  2. L

    a simple first year phys question tht i wan u engineers to solve

    no they are 100% correct :) didn't you read?
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    pH Calculation

    a neutralisation reaction will occur between the NaOH and HCl, so just look at how much of each you have, which is in excess, and what the pH will be due to this excess after neutralisation has completed (I think)
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    90s emo

    screamo/skram : * noisy sins of the insect *, the birds are spies they report to the trees, saetia, amalthea, 1000 travels of jaharawlal, analena, +other stuffz i don't listen to this stuff as much any more but it was really cool musix
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    90s emo

    moss icon (80s), indian summer, native nod, don martin three, bob tilton, days in december yeah jazz, mineral, ethel meserve etc. type stuff is good too
  6. L

    Please help!!!

    well you draw a line of best fit with your experimental data points, so it may or may not pass through the origin
  7. L

    a maths problem

    sum of n square terms starting at 1, is n(n+1)(2n+1)/6
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    physics equation.... please help

    this is what i get too
  9. L

    Natural Buffer System

    HCO3- + H+ <=> H2CO3 by shifting the equilibrium to the right (ie more carbonic acid) we reduce the concentration of H+ .'. increase the pH. Note that the bicarbonate is acting as a base. H2CO3 would usually decrease a solutions pH when it is added, as it donates hydrogen ions, but in this case...
  10. L

    pH calculation

    molar mass of Ba(OH)2 = 137.3 + 2(16.00 + 1.008) = 171.3g so there are 0.75/171.3 = 4.38 * 10-3 moles of Ba(OH)2 in the 2.0L So [OH-] = 2*(4.38 * 10-3)/2.0 as there are 2 OH- for each Ba(OH)2 [OH-] = 4.38 * 10-3 using [OH-][H+] = 10-14 for water [H+] = 10-14/ [OH-] = 2.28 * 10-12 pH =...
  11. L

    Find all complex numbers z such that Re(z^3)<0 PLEEASSE HELP

    if z = Rcis@ then z3 = R3cis[3@] for the condition to hold, what ranges of values can 3@ have? so what range does @ have?
  12. L

    Complex Solutions to A "Complex" quadratic

    do you mean x² + y² + x? so z = 0, -1
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    Why is G.P.E negative?

    ostentatious: the further away two masses are, the higher their GPE is. For convenience, we say that at the maximum distance, ie. as it approaches infinity, the absolute GPE is zero. So at any other point it will be less than this. The amount below zero it will be is equal to the amount of work...
  14. L

    Which root approximation is closer

    basically like you said apply halving the interval, which shows the root is between 0.5 and 0.75, so it lies closer to 0.5 i think that should be clear enough
  15. L

    quite a bunch of questions

    that's not what 6ii is asking ^ you just draw the circle w/ radius 1, centre (2,0) -> this is the graph of z+2, where |z|=1 then you find the lines through the origin which are tangent to the circle to find the min/max arg
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    quite a bunch of questions

    it's easier to equate coefficients as timothy + drongoski pointed out for mine, with the roots, you get things in the form n +- rt(n^2 - 1), so if a,b,c = cos[1,5,7 pi/9] you can then group things like (a + rt(a2 - 1) + a - rt(a2-1))(b + rt(b2-1) + b - rt(b2-1)) [3 like this] + (a + rt(a2))(a...
  17. L

    quite a bunch of questions

    you could solve 10) iii) by solving each quadratic, then using the sum of the roots 2 at a time = 0 for the original equation once you group the pairs together it simplifies down to 4cos[pi/9]cos[5pi/9] + 4cos[5pi/9]cos[7pi/9] + 4 cos[7pi/9]cos[pi/9] + 3 = 0 which gives the desired result
  18. L

    specific divisibility induction question

    assume true for n=k 3^{3k} + 2^{k+2} = 5M show true for n = k+1 3^{3(k+1)} + 2^{(k+1)+2)}\\ = 27\times3^{3k} + 2\times2^{k+1}\\ = 25\times3^{3k} + 2\times(3^{3k} + 2^{k+2})\\ = 5\times5\times3^{3k} + 2\times5M\\ = 5(5\times3^{3k} + 2M) maybe you were only adding one to the 3 power rather than...
  19. L

    Trick Question

    1/(1+tn) <= 1/(1+tn+1) for 0 <= t <= 1 but the equality only exists when t = 0, 1 as the integral also has all other values in the range, it can't be equal
  20. L

    Trick Question

    i don't think they can be equal
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