1) 6-(2х-9)=(18+2х)-3(х-3)
6-2х+9=18+2х-3х+9
3х-2х-2х=18-6-9+9
-х=12
х=-12
2) -4(2у-0,9) + 2,4=5,6-10у
2,4-8у+3,6=5,6-10у
10у-8у=5,6-3,6-2,4
2у=- 0,4
у= - 0,2
2а+3-1.5а+0.5=(2а-1.5а)+(3+0.5)=0.5а+3.5
при а=-3
0.5а+3.5=0.5*(-3)+3.5=-1.5+3.5=2
при а=0
0.5а+3.5=0.5*0+3.5=0+3.5=3.5
при а=4
0.5а+3.5=0.5*4+3.5=2+3.5=5.5
1)х²+2ух-х-ах+а-2ау
х(х+2у-1)-а(х-1+2у)
2)х²+2х-3х-6+4х+2=х²+3х-4=х(х+3)-4