efectuati scotand factor comun(poza)​

a) -2×8+2×5=2(-8+5)=2×(-3)=-6

b)a×(-2)+b)×(-2)=-2(a+b)

c)13×(-16)+27×(-16)=-16(13+27)=-16×40= -640

Răspuns:

Explicație pas cu pas:

21)

a)   ( - 2 ) × ( + 8 ) - ( - 2 ) × ( + 5 ) = - 6

= ( - 2 ) × ( + 8 - 5 ) =

= ( - 2 ) × 3 =

= - 6

_____________________________

b)    ( + a ) × ( - 2 ) - ( - b ) × ( - 2 ) = ( - 2 ) × ( a + b )

= ( - 2 ) × [ ( + a ) - ( - b ) ] =

= ( - 2 ) × ( a + b ) =

= - 2 a - 2 b

___________________________

c)    ( + 13 ) × ( - 16 ) + ( + 17 ) × ( - 16 ) = - 480

= ( - 16 ) × ( 13 + 17 ) =

= ( - 16 ) × 30 =

= - 480

____________________________

d)  ( - a ) × ( - 3 ) + ( - a ) × ( + 5 ) = - 2 a

= ( - a ) × ( - 3 + 5 ) =

= ( - a ) × 2 =

= - 2 a