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Math paper4 Jun. 2009 help

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moon:
I need help in NOV 2004 Q7 Please.It is diffiicult.

Ghost Of Highbury:

--- Quote from: moon on November 03, 2009, 03:58:54 pm ---I need help in NOV 2004 Q7 Please.It is diffiicult.

--- End quote ---

the whole q?

moon:
please I need a3, bii and c2 ???

wassup:

--- Quote from: moon on November 03, 2009, 03:58:54 pm ---I need help in NOV 2004 Q7 Please.It is diffiicult.

--- End quote ---
7 a)i) y = px + qx + r
      y = 4^2+(-2*4)+(-3)
      y = 5

ii) On K and L y=0
so, px + qx + r=0
     x-2x-3=0
     Solve this n u'll get x=-1, 3
K(-1,0) L(3,0)

iii) On M x=0
so, y=r
     y=-3
M(0,-3)

b)i) Upside down
ii) Eqn, will be x^2=y, so just put some values n get the shape of graph

c)i) c=0 because it passes through d origin
ii) (3,0) (4,8)
put these in the eqn.

3^2a + 3b = 0
4^2a + 4b = 8

solve these n u'll get a = 2, b = –6

Ghost Of Highbury:

--- Quote from: moon on November 03, 2009, 04:17:23 pm ---please I need a3, bii and c2 ???

--- End quote ---

for aiii

best wud be to draw the graph, and see where the minimum point lies. write its cordinates

for confirmation u can use differentiation

dy/dx = 2x - 2

2x - 2 =0

2x = 2

x = 1 substituting y = 4

dont bother if u dont understand this

for bii

u know then the value are applied in the equation

u r left with only y = x2 which is a parabola and passes through the origin (0,0)

for cii

it says it passes through the origin
which means, c =0

u r left with

y= ax^2 + bx

substitute the cordinates (3, 0) and (4, 8).

to get

0 = 9a + 3b

and

8 = 16a + 4b

from the second we can get

a = 8-4b / 16
substitute this in the first to get
72 - 36b
--------  = -3b
     16

72 - 36b = -48b

solve to get

b = -6 and a = 2

@wassup - for aiii - it is not they-axis, its a line of symmetry

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