八、九题请学霸帮忙,谢谢
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8、
a³b³-1/2ab²+b²-2a³b³+0.5ab²+b²+a³b³-2b³-3
=(a³b³+a³b³-2a³b³)+(0.5ab²-1/2ab²)+b²+b²-2b³-3
=2b²-3b³-3
=2×(-0.25)²-3×(-0.25)³-3
=2×1/16+3×1/64-3
=1/8+3/64-3
=8/64+3/64-192/64
=-181/64
9、
x/2t=y/t=z/3t
x/y=2→x=2y
y/z=1/3→z=3y
3x+2y+z=22t
即6y+2y+3y=22t
y=2t
则x=4t,z=6t
(4x-3y)/(2z-5t)
=(4×4t-3×2t)/(2×6t-5t)
=(16t-6t)/(12t-5t)
=10/7
a³b³-1/2ab²+b²-2a³b³+0.5ab²+b²+a³b³-2b³-3
=(a³b³+a³b³-2a³b³)+(0.5ab²-1/2ab²)+b²+b²-2b³-3
=2b²-3b³-3
=2×(-0.25)²-3×(-0.25)³-3
=2×1/16+3×1/64-3
=1/8+3/64-3
=8/64+3/64-192/64
=-181/64
9、
x/2t=y/t=z/3t
x/y=2→x=2y
y/z=1/3→z=3y
3x+2y+z=22t
即6y+2y+3y=22t
y=2t
则x=4t,z=6t
(4x-3y)/(2z-5t)
=(4×4t-3×2t)/(2×6t-5t)
=(16t-6t)/(12t-5t)
=10/7
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