SHARING.... -experiences of teaching maths as a hobby for over 50 years to school and college students. -challenges in project management and the common sense approach to it from old classics.

Sunday, March 22, 2015

INTEGRATION
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Use series to approximate the definite integral I to within the indicated accuracy.
I =
0.5 x3e?x2dx
integral.gif
0
    (|error| < 0.001)
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INFINITE SERIES
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Will the iteration xn+1 = xn + sin(xn) converge when x0 is sufficiently close to the root r = Pi ? If so, what is the order of convergence? (Justify your answer theoretically without actually iterating the formula.)
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Tuesday, March 17, 2015

MAXIMA-MINIMA......A DIFFERENT PROBLEM
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SURFACE AREA = S = 2[XY+YZ+ZX] = 7000
XY+YZ+ZX=3500……………………………….1
EDGE LENGTH = P= 4[X+Y+Z]=440
X+Y+Z=110……………………………..2
VOLUME=V=XYZ.................................3


AT THE OUT SET IT IS CLEAR THAT USING CRITERIA FOR LOCAL MAXIMA/MINMA
THE SOLUTION IF ANY  HAS TO BE AT ...X=Y=Z...BUT THIS IS CLEARLY NOT POSSIBLE SINCE ..THIS LEADS TO .....3X^2=3500....OR...X=34.16 FROM EQN. 1 .AND.......
.....3X=110...OR...X=36.7 FROM EQN.2 WHICH ARE CONTRADICTORY ..
SO THE MAXIMA/MINIMA WILL ONLY BE AT BOUNDARIES WHICH HAVE TO BE EVALUATED...

FROM EQN. 2 ….X = 110-Y-Z………….4



PUTTING EQN. 1





Z= [3500-XY]/[X+Y]………………..5



PUTTING EQN. 5 IN EQN.4




X=110-Y- [3500-XY]/[X+Y]




Y^2+Y[X-110]+[X^2-110X+3500] =0..



 Y= 0.5*[(110-X)+(-3X^2+220X-1900)^0.5] …OR….

Y= 0.5*[(110-X)-(-3X^2+220X-1900)^0.5]


WE FIND DISCRIMINANT D = -3X^2+220X-1900 -
 D = -[X-10][3X-190 ] ..=0 ..............AT …X = 10 AND ….X= 190/3=63.3333



SO WE GET THE DIMENSIONS &VOLUME AT THE BOUNDARIES AS FOLLOWS
NOTE THAT THE FUNCTIONS BEING SYMMETRIC IN X,Y,Z , WE CAN TAKE
POINTS AS [10,50,50];[50,50,10];[50,10,50]…AND…


[190/3,70/3,70/3] ; [70/3,190/3,70/3] ; [70/3,70/3,190/3]









X Y Z1 Z2 V=


10 50 50 50 25000 MINIMUM 
50 50 10 10 25000 MINIMUM 
50 10 50 50 25000 MINIMUM 
63.33333 23.33333 23.33333 23.33333 34481.481 MAXIMUM 
23.33333 63.33333 23.33333 23.33333 34481.481 MAXIMUM 
23.33333 23.33333 63.33333 63.33333 34481.481 MAXIMUM 


MATRICES
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A IS INVERTIBLE ...HENCE A IS NOT SINGULAR ..THAT IS |A| IS NOT EQUAL TO ZERO ..
AS WE KNOW | A | ...DETERMINANT OF ANY SQUARE MATRIX A ...CAN BE FOUND USING CO FACTOR EXPANSION USING ANY PARTICULAR ROW OR COLUMN ..SO IF ....A = [a(I,J)]THEN ...|A|=\sum a(I,K)*A(I,K).....FOR K=1 TO N , WHERE A(I,K) IS TRHE COFACTOR OF THE ELEMENT a(I,J)....EXPANDING BY ANY ROW ...
SINCE A TRANSPOSE = [a(J,I)] WE GET .....|A TRANSPOSE | = \sum a(I,K)*A(I,K).....FOR K=1 TO N ...EXPANDING BY ANY COLUMN
SO WE CONCLUDE ..
|A| = | A TRANSPOSE |..............................................PROVED
SINCE DETERMINANT OF PRODUCT OF 2 EQUAL RANKED SQUARE MATRICES = PRODUCT OF DETERMINANTS OF THE 2 WE GET ..
A * A INVERSE = I
|A * A INVERSE| = | I |.........| A | * |A INVERSE | = 1
|A INVERSE | = 1 / | A | | ........PROVED

Sunday, March 15, 2015

DIFFERENTIAL EQUATIONS ....SYSTEMS OF LINEAR EQUATIONS
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