Question

先化简,再求值xy-(4/3y+4/3)-(3/2x+xy+2),其中x=2/3,y=-3/4

解解呀！有赏金！我现在就要答案！

Answer 1

xy-(4/3y+4/3)-(3/2x+xy+2)
=xy-4/3y-4/3-3/2x-xy-2
=-4/3y-3/2x-10/3
=1-1-10/3
=-10/3

Answer 2

0<=t<=1
v=mt
则7.5=m*1
m=7.5

1<t<8,v=7.5

8<=t<=10
v=kt+b
过(8,7.5),(10,0)
7.5=8k+b
0=10k+b
相减
2k=-0.5
k=-0.25
b=-10k=2.5
所以v=-0.25t+2.5

v=7.5t，0<=t<=1
v=7.5，1<t<8
v=-0.25t+2.5，8<=t<=10