^ 表示乘方
关于x的多项式ax^4+4x²-1/2是四次三项式,它与3x^b+5x是同次多项式,则：b=4

1/2b³-2b²+3b-4
=(1/2)×4³-2×4²+3×4-4
=(1/2)×64-2×16+3×4-4
=32-32+12-4
=8