9х2-12х+4-9х2+1=-2х
-10х=-3
Х=0,3
(5а-9)(5а+9)=0
5а-9=0
5а=9
А=1,8
Ctgt=cost/sint
sin(-t)=-sint
cos(2π-t)=cost
ctgt*sin(-t) + cos(2π-t)=cost*(-sint)/sint + cost=-cost+cost=0
-2,5(z+v-z)= -2,5z-2,5v+2,5z
<em>0.2*(3х-3.5)-5 (4.8-х)+0.7 =0.6х-0.7-24+5х+0.7=</em><em>5.6х-24</em>