<span>(х+3)2=0
</span><span>Х2+9=0
</span><span>Х2=9
</span><span>Х=3</span>
8z•5z+8z•4 -2•5z-2•4=4z•8z+4z•8 - 1•8z -1•8
40z2(2-это квадрат)+ 32z - 10z - 8= 32z2 + 32z -8z-8
40z2+32z-10z-8-32z2-32z+8z+8=0
8z2-2z=0
2z(4z-1)=0
2z=0........... 4z-1=0
z=0..............4z=1
..................... z=1/4
5х-7х-7=9
-2х=9+7
-2х=16
х= - 8
<span> (m-mn)-(n-mn)+(m+n)=<span> m<u>-mn</u>-<u>n</u>+<u>mn</u>+m+<u>n=</u>2m</span></span>