3)
(y+4)³+(3y+1)³-7y²(4y+9)=-24y²+8
(y+4)³+(3y+1)³=-24y²+8+7y²(4y+9)
(y+4+3y+1)((y+4)²-(y+4)(3y+1)+(3y+1)²)=-24y²+8+28y³+63y²
(4y+5)(y²+8y+16-(3y²+12y+y+4)+9y²+6y+1)=28y³+39y²+8
(4y+5)(10y²+14y+17-3y²-13y-4)=28y³+39y²+8
(4y+5)(7y²+y+13)=28y³+39y²+8
28y³+35y²+4y²+5y+52y+65-28y³-39y²-8=0
57y+57=0
57y=-57
y=-1
Ответ: -1
4.
(4y-5)³-(4y+5)³=48y(1-10y)-10
(4y-5-(4y+5))((4y-5)²+(4y-5)(4y+5)+(4y+5)²)=48y-480y²-10
(4y-5-4y-5)(16y²-40y+25+16y²-25+16y²+40y+25)=48y-480y²-10
-10(48y²+25)=48y-480y²-10
-480y²+480y²-250-48y=-10
-48y=-10+250
-48y=240
y= -5
Ответ: -5