Question

Zad 1 str 126 "matematyka wokół nas"

a) (-7) x (-8)

b) 4 x (10 1/4)

c) 0.4 x (-0,9)

d) (-5/8) - 1.6

Zad 2 str 125

Wykonaj działania stosując przemienność i łączność mnożenia

a) (-1.2) x 2.5 x (-10) x 4 x (-2)

b) (-2/3) x 5/8 x 1 1/2 x (-8/15) x 0.3

c) 0.007 x 1.3 x (-1000) x (-20)

d) (-5/6) x (-2.5) x 2 2/5 x 2 x (-1)

Answer 1

Rozwiązanie:

 

Zad.1 

a) (-7) x (-8)= 56


b) 4 x (10 1/4)=4x41/4=41


c) 0.4 x (-0,9)= - 0,36


d) (-5/8) - 1.6= - 0,625 - 1,6= - 2,225

 

 zad.2

a) (-1.2) x 2.5 x (-10) x 4 x (-2)=  - 3 x (-10) x (-8)= - 240



b) (-2/3) x 5/8 x 1 1/2 x (-8/15) x 0.3 = - 10/24 x 3/2 x (- 24/150)= 

- 30 /48 x   (- 24/150)  = 1/10



c) 0.007 x 1.3 x (-1000) x (-20)= 0,0091 x 20000 = 182



d) (-5/6) x (-2.5) x 2 2/5 x 2 x (-1)= 125/60 x 2,4 x (-2)= 125/60 x (-4,8)= 

125/60 x (-48/10) = 25/15 x 12/2 = 300/30 = 10

 

Answer 2

1.

a) (-7) * (-8)=56

b) 4 * 10 1/4=4 * 41/4= 41

c) 0.4 * (-0.9)= -0.36

d)(-5/8)-1.6=(-0.625)-1.6=(-2.225)

2.

a) [(-1.2)*2.5]*[(-10)*(-2)]*4=(-3)*20*4=(-3)*60=(-240)

b) (-2/3)*5/8*3/2*(-8/15)*3/10=[(-2/3)*3/2]*[5/8*(-8/15)]*3/10=

[(-1)*(-1/3)]*3/10=1/3*3/10=1/10

c)[0.007*(-1000)]*[1.3*(-20)]=(-7)*(-26)=182

d)(-5/6)*2 1/2 *2 2/5 *2 *(-1)=(-5/6)*[(-5/2)*12/5]*2*(-1)=

[(-5/6)*(-6)]*2*(-1)=(5*2)*(-1)=10*(-1)=-10