Apuntes Del 4 De Septiembre Del 2008

SISTEMA DE ECUACIONES 2*2

1.

2x + 3y = 10 Ec. 1

4x + y = 5 Ec.2

* Despejar x De la Ec. 1* ...........

2X = 10-3Y

___________ Ec. 3

2

* Despejar x De la Ec. 2* ...........

4x = 5 -Y

X= 5-Y

_______ Ec. 3

4

* Ec. 3 y Ec. 4 Igualar * .......

10 - 3y 5 - y

________ = ________

2 4

4 (10 -3y ) = 2 ( 5 - y)

40 - 12y = 10 - 2y

-12y + 2y = 10 - 40

-10y = -30

y = 30/-10

y= 3

* Tomo Ec. 3 *......

x= 10 - 3 (3)

_______

2

x= 10 - 9

______

2

x= 1/2

____________________________________________________________________

2.

-3a + 2b = 6

a + 3b = 18

-3a = 6 - 2b 18 - 3b

_______ =________

-3 1

1( 6 - 2b ) = -3 ( 18 - 3b )

6 - 2b = -54 + 9b

-2b + 9b = -54 - 6

11b = -60

b = - 60/-11

b = 5.45

= 5 5/11

a = 18 - 3 (60/11)

a = 18 180

__ - ____

1 11

a = 198 - 180

________

11

a = 18/11

a = 1 7/11

a = 1.63