1. 3D
2009 12 07
x−y =1
x − 2y = −2
x−y =1 x − 2y = −2
x −2 0 2 x −2 0 2
y y
y
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
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−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
6
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
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−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
-
O x
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
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−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
1

2. 4x + 3y = −5
3x + 2y = −4
a a
2x − 3y = a + 8
−4x + 6y = 3a − 1
2

3. 186 cm 182 cm
0.1%
M 5% $ 23 4
$ 0.1
J. S. Bach Well Tempered Clavier 12
5.61% A 440
Hz A 4 F Hz
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440 Hz ? Hz
3

4. $ 4000 4% 5
$ 4000 4% 5
$ 0.1
$ 68 000 5%
pass with flying colours!
4