已知a,b满足a눀+b눀+5⼀4=2a+b,求代数式27a대-54a눀b+36ab눀-8b대的值

2025-05-23 20:33:01
推荐回答(3个)
回答1:

a²+b²+5/4-2a-b=0
(a²-2a+1)+(b²-2b+1/4)=0
(a-1)²+(b-1/2)²=0
则:a=1,b=1/2
则:27a³-54a²b+36ab²-8b³=(3a-2b)³=8

回答2:

a²+b²+5/4=2a+b
a²-2a+1+b²-b+1/4=0
(a-1)²+(b-1/2)²=0
a-1=0
b-1/2=0
a=1
b=1/2

27a³-54a²b+36ab²-8b³
=27-54*1/2+36*1/4-8*1/8
=27-27+9-1
=8

回答3:

解析:2a√(3ab^2)-b/2*√27a^3+3ab√(a/3)
=2ab√3a-3ab/2*√3a+ab√3a
=3ab/2*√3a