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  1. Sirius Black

    linear algrebra question

    Consider the vector space R3. Find four vectors a, a',b,b' such that A=Sp{a,a'} B=Sp{b,b'} and A+B=R3 and AnB(A intesects B)=Sp{(1,1,1)} does anyone know how to make two planes into a space i.e. R3...
  2. Sirius Black

    Q!

    The 4-digit number 2652 is such that anyu two consecutive digits from it make a multiple of 13. Another number N has the same property but with 100 digits, and begins with 9. what is the last digit of N? choices: (a)2 (b)3 (c)6 (d) 9 N= 913913913.... SO the answer is d? thanx in advance:)
  3. Sirius Black

    could any1 help on this plz

    If you factorise x<sup>4</sup>-20x<sup>2</sup>+16=(x<sup>2</sup>+4x-4)(x<sup>2</sup>-4x-4) OR=(x<sup>2</sup>+2sqrt7 x+4)(x<sup>2</sup>-2sqrt7 x+4) by using the result of x<sup>4</sup>+Ax<sup>2</sup>+B=(x<sup>2</sup>+ax+b)(x<sup>2</sup>-ax+b) but the 4 roots to...
  4. Sirius Black

    help on Q4 + Q15 in phys specimen paper

    In the solution provided by Success One Book Q4-A Why isn't the hammer experiencing centripedal acceleration towards the center of the Earth when its dropped from geosychronous orbit as in (B)? Q15-D Doesn't radio wave always travel at C regardless of medium? if so, if the frequency is the...
  5. Sirius Black

    2003 HSC Q17 (c)

    could any1 explain the trends in the graph plz (in particular the peak) thanx
  6. Sirius Black

    help on production of polyethylene

    Part 1 of syllabus says that " outline teh steps in the production of polyethylene as an example of acommercially andindsutrially important polymer" Is there any difference between commericial and industrial methods to produce polyethylene? :rolleyes: thanx a lot
  7. Sirius Black

    two confusing dot points

    describe factors that affect an electrolysis reaction -effect of concentration -nature of electrolyte -nature of electrodes This looks quite similar to the prac"plan and perform a first-hand investigation and gather first-hand data to identify the factors that affect the rate of an...
  8. Sirius Black

    ?

    -In calculation questions, how many significant figures should we use for our final answer? -In any expt, what are the potiential sources of error? Thanx in advance
  9. Sirius Black

    existence of the aether model

    My teacher said we cannot simply say that the null result of Michelson-Morley's experiment disproved the existence of aether model as it just FAILED to find any evidence of aether's existence. However, Einstein's first postulate says that "the laws of physics are the same in all frames of...
  10. Sirius Black

    ?

    · Identify the use of electrolysis as a means of cleaning and stabilising iron, copper and lead artefacts Isn't the electrolysis process used to restore the artefacts rather than cleaning and stabilising?
  11. Sirius Black

    very quick q!

    hi does any1 know how to calculate gravitational field strength? :cool:
  12. Sirius Black

    help on a dot point

    outline some examples of the occurance, production and uses of ester could anyone tell me what are some natural esters? :cool:
  13. Sirius Black

    definition wanted:)

    could any1 tell me meaning of the term "conventions of narratives" in Module A telling stories? Thanx in advance:D
  14. Sirius Black

    quick answer needed for projectile motion

    when an object is fired from a ground, both of its angle of projection and initial velocity are given. If the question asks you to find its final velocity, can u just simply state that the nature of this motion (when resistance is neg.) is actually a mirror reflection, so the final v =intial u...
  15. Sirius Black

    Help on a simple question

    A person stood on scales thqat were designed for the Earth whilst on Mars. The scale gave a reading of 50kg. Would the actual mass of the person be 50kg since the mass is independent of the location of the body right? the part which confused me is that the basic principle involves in the...
  16. Sirius Black

    a q

    Luigi Galvani first generated an electric current by using two different metal wires place separately on a freshly extracted frog muscle. List two chemical conditions, which enabled the generation of the electric current. The only condition that I know is “two different metals formed a...
  17. Sirius Black

    roots of polynomial with real coeff

    If (2-sqrt3) is a root for a polynomial with real coefficients, is 2+sqrt3 also a root I thought this rule only applied to complex root and its conjugate right? but the solution says it it the way i stated above, which means (2+sqrt3) is a conj. of (2-sqrt3)?! Could anyone help?
  18. Sirius Black

    Hard Integration q

    prove that if Let U<sub>n</sub>=<MATH>&int; xcos<sup>n</sup>x dx</MATH> from o to pi/2 then U<sub>n</sub>=(n-1)/n U<sub>n-2</sub>-1/n<sup>2</sup>
  19. Sirius Black

    help

    how to use sodium carbonate solution/bromine water and/or acidified potassium dichromate solution to distinguish b/w 1-butanol and cyclohexane? Edit: could we just use acidified potassium dichromate solution oxidise butanol into butanopic acid and then use sodium carbonate to tell the acid...
  20. Sirius Black

    Qs on water quality monitoring

    Q1. Identify two common indicators of water quality that would be the most useful in monitoring waste water from a fruit cannery. Justify your choices. [could anyone tell me what the main contaminations are present in the waste water from fruit cannery?] btw, could any1 summarise the main...
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