Question

oblicz najprostszym sposobem :

a) 12 x (-3) - (-4) x 12 b) 24 x (-3) - (-4) x 12

c) (- 16 ) : 4 + (-24) : 4 d ) (-36) : (-7) + 15 : (-7)

e) 14 : (-3) - (-8) : 3

Answer 1

a)   {12a-7b=-16

{a-3b=-69

 

{12(3b-69) -7b = -16

{a=3b - 69

 

{36b - 828 - 7b = -16

{a=3b-69

 

{36b-7b= -16+ 828

{a=3b-69

 

{29b= 812   /:29

{a=3b -69

 

{b=28

{a=3*28 - 69

 

{b=28

{a= 15

 

b)   {11x+17y=45

{13x+y=15     /* -17

 

{11x+17y = 45

{-221x -17y = -255

 

11x-221x-17y+17y= 45 - 255

210x=210   /:210

x=1

 

11*1 +17y=45

17y = 45 - 11

17y= 34  /:17

y=2

 

{x=1

{y=2

 

c){8a+9b=36

{a-16b=210  /*-8

 

{8a+9b=36

{-8a + 128b = -1680

 

8a+9b-8a+128b = 36 - 1680

137b= -1644    /:137

b=-12

 

a-16 *-12 =210

a + 192 = 210

a=210-192

a=18

 

{a=18

{b=-12

Answer 2

a)12·(-3)-(-4)·12=-36-(-48)=36+48=84

b)24·(-3)-(-4)·12=-72-(-48)=-72+48=-24

c)-16:4+(-24):4=-4+(-6)=-10

d)-36:(-7)+15:(-7)=36/7 · (-7/15)=-36/15=-2⅖

e)14:(-3)-(-8):3=-14/3 - (8/3)=-14/3 +8 /3 = -6/3=-2