= 6,3х-4-21,6х-0,9 = -15,3х-4,9
А) -x=-2
x=2
б) 2-2x=x-7
2+7=x+2x
9=3x
x=3
A)=0.8x²
б)=13/20a²b
............................................
(3х-1)*(2х+6)=8(2х+3)
6x+18x-2x-6=16x+24
6x+18x-2x-16x=24+6
6x=30
<span>x=30:5
x=5</span>
(5а-3b)(5a+3b)=25a^2-9b^2