8-10x+15=13-6x
-10x+6x=13-15-8
-4x=-10
x=-10:(-4)
x=2.5
4ab-8*3-8*2+2ab = 4ab-b*3-64+2ab = 6ab-b*3-64
25cˇ2+80c+64-cˇ2+20c-100=24cˇ2+100c-36=4(6cˇ2+25c-9)
4(6cˇ2+25c-9)=0
6cˇ2+25c-9=0, D=625+216=841, V841=29
c1=1/12 (-25+29)=1/3
c2=1/12(-25-29)=-9/2
(5c+8+c-10)(5c+8-c+10)=(6c-2)(4c+18)=0,c1=1/3,c2=-9/2
15-3x+0,5+1=9
-3х=9-15-0,5-1
-3х=-7,5
х=2,5
2х-1+1=9
2х=9
х=4,5