1) х(3х+5)-1=х(х-4)
3х²+5х-1=х²-4х
3х²-х²+5х+4х-1=0
2х²+9х-1=0
2) (7х-1)(2+х)=(х-4)(х+4)
14х-2+7х²-х=х²-16
7х²-х²+14х-х-2+16=0
6х²+13х+14=0
3) (6+х)²=(х-2)(3-х)
36+12х+х²=3х-6-х²+2х
х²+х²+12х-3х-2х+36+6=0
2х²+7х+42=0
4) х(8-3х)=(5х-1)²
8х-3х²=25х²-10х+1
-3х²-25х²+8х+10х-1=0
-28х²+18х-1=0
28х²-18х+1=0