1. (3х+4)(5х+1)=0
3х+4=0 х= -4/3
5х+1=0 х=-1/5
2. 5х(х+2)=0 разделим обе части на 5
х(х+2)= -2
х1=0 х2=0
3. (3,5х+0,7)(1,2-2х)=0
(7/2х+7/10)(6/5-2х)=0
7/2х+7/10=0
6/5-2х=0
х1=-1/5 х2=3/5
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