Question

1 )3(x-7)+5x
2 )3(a-b)-2(a+b)
3 )7(0.5a+1)+1.5a-9  при a=-0.8

Answer 1

1 )3(x-7)+5x = 3х-21+5х=8х-21
2 )3(a-b)-2(a+b)= 3а-3b-2a-2b=a-5b
3 )7(0.5a+1)+1.5a-9                   при a=-0.8
3.5a+7+1.5a-9=6.5a-2=6.5*(-0.8)-2= - 5.2-2= -7.2