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
Y=log7(4-x^2)
4-x^2>0
2^2-x^2>0
(2-x)(2+x)>0
2-x>0 2+x>0
-x>-2 x>-2
x<2