1) =28с²+14с-49-14с-с²=27с²-49
2) =-18с²-6с-9+6с-с²=-19с²-9
3) =54с²+12с-36-12с-с²=53с²-36с
3log(x)y-1/log(x)y=4
3•log(x)y+1/log(x)y=4
log(x)y=t
3t^2-4t+1=0
t1=(2+√4-3)/3=1
t2=1/3
log(x)y=1
y=x
log(x)y=1/3
y=x^(1/3)
a остальные сам сделай
5/30-8/30=-3/30=-0.1
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