X(x-4)+(3-x)(3+x)= -6
x²-4x+9-x²= - 6
- 4x= -6 - 9
4x=15
x=15:4
x=3.75
81y²-100=0
(9y-10)(9y+10)=0
9y-10=0 9y+10=0
9y=10 9y= -10
y1=1 1/9 y2= - 1 1/9
(9c²+d²)(3c-d)(3c+d)=(9c²+d²)(9c²-d²)=81c^4 - d^4
(5x^4 - 7y²)(5x^4 +7y²)=25x^8 - 49y^4
81x²+4y²>36xy -8
81x²-36xy+4y² > -8
(9x -2y)(9x-2y) > -8
Ах-ау+5х-5у=a(x-y)+5(x-y)=(x-y)(a+5)