已知a与b互为相反数,c与d互为倒数,x=3(a-1)-(a-2b),y=cd+c(a+b),求3x-2y

2025-05-20 13:11:13
推荐回答(2个)
回答1:

由题意知:
a=-b
c=1\d
故:
x=3(-b-1)-(-b-2b)=-3
y=1\d*d+1\d*(-b+b)=1
故:
3x-2y=3*(-3)-2*1=-1

回答2:

因为a,b互为相反数,
所以a + b = 0
因为c,d互为倒数,
所以cd = 1

x
= 3(a - 1) - (a - 2b)
= 3a - 3 - a + 2b
= 2a + 2b - 3
= 2(a + b) - 3
= -3

y
= cd + c(a + b)
= 1 + 0
= 1

所以
3x -2y
= 3×(-3) - 2×1
= -9 - 2
= -11