Question

a)

∑5(x+3)-3(y+4)=-1

(2x-y)-(3x+2y)=8

b)

∑-2(x+y)+5(2x+y)=12

4(y-x)+3(x-y)=-7

Dam naj ******************

Answer 1

nie bardzo wiem o co chodzi, ale może o x i y?

 

a:

 

 ∑5(x+3)-3(y+4)=-1

   (2x-y)-(3x+2y)=8

 

5x  +15 -3y-12 = -1

2x -y -3x -2y = 8

 

5x-3y= -4

-x -3y = 8    // -1

 

 5x    -3y= -4

   x +3y = -8

_________

   6x = -12

x= -2

y= (-8-x)/3 = (-8+2)/3 = -6/3 = -2

 

b)

 

 ∑-2(x+y)+5(2x+y)=12

       4(y-x)+3(x-y)=-7

 

-2x -2y +10x +5y = 12

 4y - 4x +3x -3y = -7      

 

8x +3y = 12

-x +y  =  -7      // (-3)

 

8x +3y = 12

3x -3y  =  21    

____________

11x  = 33

x = 3

y = x - 7 = 3 - 7 = -4