1)
(x-y)A = x^2·y^2 -x^3·y <=>
(x-y)A = -(x-y)x^2·y <=>
A= -x^2·y, x≠y
2)
(-9x^2 +A)y = B +y^4 <=>
y(-9x^2 +A) = y(B/y +y^3), y≠0 <=>
-9x^2 +A = B/y +y^3
A= y^3
B/y= -9x^2 <=> B= -9x^2·y, y≠0
3)
(1,4 -A)3x = B -0,6x^3 <=>
3x(1,4 -A) = 3x(B/3x -0,2x^2), x≠0 <=>
1,4 -A = B/3x -0,2x^2
A= 0,2x^2
B/3x= 1,4 <=> B= 4,2x, x≠0
4)
A(B -x^2·y^5 +5y^6) = 8x^3·y^3 +5x^3·y^8 -C <=>
A(B -x^2·y^5 +5y^6) = x^3·y^2(8y -C/x^3·y^2 +5y^6), x,y≠0
A=x^3y^2
B=8y
-C/x^3·y^2= -x^2·y^5 <=> C= x^5·y^7, x,y≠0
6х^2 +21x-2x-7-6x^2+5x-6x+5=7
21x-2x+5x-06x=7+7-5
18x=9
x=9/18
x=1/2;0,5
(8√6+6)(8√6-6)=(8√6)²-6²=64*6-36=384-36=348.