5(3a²-b)+3(b-b²)=15a²-5b+3b-3b²=15a²-3b²-2b
a=1/5
b=5/6
15*1/5²-3*5/6²-2*5/6=15*1/1
25-3*25/36-10/6=3/5-25/12-1 2/3=
36/60-2 5/60-1 40/60=-3 9/60=-3 3/20=-3,15
4(c²-2b²)+5(c-c²)=4c²-8b²+5c-5c²=-c²-8b²+5c
b=3/4
c=1/3
(-1/3)²-8*3/4²+5*1/3=1/9-8*9/16+1 2/3=
1/9-4 1/2+1 2/3=2/18-4 9/18+1 12/18=
-4 7/18+1 12/18=-2 13/18
a(1-3b²)-3b(2-ab)=a-3ab²-6b+3ab²=a-6b
a=-3,1
b=-0,5
-3,1-6*(-0,5)=-0,1
2x(3-xy)-y(4-2x²)=6x-2x²y-4y+2yx²=
6x-4y
x=-0,3
y=-0,2
-0,3*6-4*(-0,2)=-1,8+0,8=-1