Докажите тождество: 1) -0,2(4b - 9) + 1,4b = 0,6 + 1,8 2) (5а - 3b) - (4 + 5a - 3b) = -4 3) 5(0,4 - 0,3) + (0,8 - 0,6x) = 1,4x - 0,7 4) 1/9(3y - 27) - 2(1/12y - 1,5) = 1/6y

1) -0.2(4b-9)+1.4b=-0.8b+1.8+1.4b=0.6b+1.8       0.6b+1.8=0.6b+1.8
2) (5a-3b)-(4+5a-3b)=5a-3b-4-5a+3b=4                4=4 
3) 5(0.4-0.3)+(0.8-0.6x)=2-1.5+0.8-0.6x=1.3-0.6x   1.3-0.6x≠1.4x-0.7      
4) 1/9(3y - 27) - 2(1/12y - 1,5)=y/3-3-1/6y+3=y/3-1/6y  y/3-1/6y≠1/6y