4-2x = -4x+5
4-2x+4x-5
4+2x-5=0
-1+2x=0
2x=1
x=1/2
x=0.5
См. вложение
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а4=а1+3d=10+3*(-0.1)=10-0,3=9,7
1) = 2,4х-8,4-2х+0,4=0,4х-8; при х= 4 1/6
4/10 * 25/6 = 100/60=10/6=5/3=1 2/3
2) = -3х+9-6х-8=-9х+1; при х=-2/3
-9 * (-2/3) +1= 6+1=7
3) = 2а-24-14а+21=-12а-3; при а=1/3
-12 * 1/3 -3=-4-3=-7