轻松上初中数学23页答案
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.(-7y)+12y-8y
=12y-(7y+8y)
=12y-15y
=3y
5a-2/3b+4a-1/3b
=(5a+4a)-(2/3b+1/3b)
=9a-b
(-3)×2ab+5ab×6
=-6ab+30ab
=24ab
根号19p+2根号19p+根号19
=根号19×（p+2p+1）
=3根号19p+根号19
=4根号19p
19(1).2/7x+2/7x-2/5x+39
=4/7x-2/5x+39
=6/35x+39
(2).2/7×35+2/7×35-2/5×35+39
=20-14+39
=6+39
=45
20.（题目略）
(12x-1/4)×12-(5x+1/6)×12=x/3×12
36x-3-10x-2=4x
26x-4x=5
x=5/22
（题目略）
(2x-1/0.7)×21=x/0.3×21-1/7×21
60x-70x=30-3
x=-2.7
=12y-(7y+8y)
=12y-15y
=3y
5a-2/3b+4a-1/3b
=(5a+4a)-(2/3b+1/3b)
=9a-b
(-3)×2ab+5ab×6
=-6ab+30ab
=24ab
根号19p+2根号19p+根号19
=根号19×（p+2p+1）
=3根号19p+根号19
=4根号19p
19(1).2/7x+2/7x-2/5x+39
=4/7x-2/5x+39
=6/35x+39
(2).2/7×35+2/7×35-2/5×35+39
=20-14+39
=6+39
=45
20.（题目略）
(12x-1/4)×12-(5x+1/6)×12=x/3×12
36x-3-10x-2=4x
26x-4x=5
x=5/22
（题目略）
(2x-1/0.7)×21=x/0.3×21-1/7×21
60x-70x=30-3
x=-2.7
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