1)(х+3)*(х-2)-(х+4)*(х-1)=3х
х²+3х-2х-6 -(х²+4х-х-4)=3х
х-6-3х+4=3х
-2х-2=3х
-2х-3х=2
-5х=2
х=-2\5=-0,4
2)15х²-(3х-2)(5х+4)=16
15х²-(15х²+12х-10х-8)=16
-2х+8=16
-2х=16-8
-2х=8
х=-8\2
х=-4
3)(2х+6)(7-4х)=(2-х)(8х+1)+15
14х+42-8х²-24х=16х-8х²+2-х+15
-8х²-10х+42=-8х²+15х+17
-10х+42=15х+17
-10х-15х=17-42
-25х=-25
х=1
4)(х+7)(х-2)-(х+4)(х+3)=-2
х²+7х-2х-14-(х²+4х+3х+12)=-2
5х-14-(7х+12)=-2
5х-14-7х-12=-2
-2х=-2+12+14
-2х=24
х=-24\2
х=-12