Question

Rozwiąż układy równań metodą przciwnych współczyników:
a)

2x-3y=7

3x-5y=11

b)

5p-2r=21

3p+5r=-6

c)

2x-3y=10

5x+5y=0

e)

4x+5y=12,3

3x-2y=-4

f)

3x-0,2y=35

2,5x-5y=5

PLIS na jutro a ja z maty zagrożony !!!

Answer 1

     2x-3y=7          / *(-3)                           2x-3y=7       / * (-5)
     3x-5y=11        / * 2                              3x-5y=11     / * 3
     -6x+9y= -21                                        -10x+15y= -35

+    6x-10y= 22                                    +       9x-15y=33
___________                                        ____________________  
         -y= -1   /(-1)                                             x=-2
          y=1                                           


5p-2r=21   / * (-3)                                       5p-2r=21   / *5

3p+5r= -6   / * 5                                          3p+5r= -6   / 2
-15p+6r= -63                                               25p-10r= 105
15p+25r=-30                                               6p+10r=-12
____________                                           _______________
     31r= - 93       /31                                                31p= 93   / 31
       r= 3                                                                      p=3

2x-3y=10    / *(-5)                                                 2x-3y=10  / * 5           
5x+5y=0     / *2                                                     5x+5y=0    / * 3
-10x+15y= -50                                                       10x-15y= 50
  10x+10y=0                                                           15x+15y= 0
_______________                                                   __________

       25x= -50  / 25                                                         25x= 50   / 25
     x= -2                                                                              x=2

 

 

4x+5y= 13,3    / *(-2)                                                    4x+5y=13,3   *2
4x-2y= -4        / * 2                                                       4x-2y= -4     *5
-8x-10y= -39,9                                                             8x+10y= 39,9
 8x-4y= -8                                                                    20x-10y= -20
_________                                                                   ___________

     -14y= 47,9  / (-14)                                                       28x= 19,9
         y= ~`3,42                                                                    x=0,71

3x-0,2y=35  / *10                                          3x-0,2y=35   / * 10
2,5x-5y=5   / *10                                           2,5x-5y= 5     / * 10
30x-2y=350    / *(-25)                                   30x-2y=350          / * 25
25x-50y=50     / 30                                       25x- 50y= 50         * (-1)
-750x-50y= -8750                                           750x-50y= 8750
 750x-150y= 150                                             -25x+ 50y= -50
______________                                              ____________
        -200x= -8600                                                     750x= 8700  / 750
              x= 43                                                               x= 11,6

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