3 1/2 - 1 2/3 = 3 3/6 - 1 4/6 = 2 9/6 - 1 4/6 = 1 5/6
1) (х-5)^2-9=(x-5-3)(x-5+3)=(x-8)(x-2)
2)x^2+2xy+y^2-4=(x+y)^2-4=(x+y-2)(x+y+2)
2х(х+1)+(х-4)(х²+4х+16)=2х²+2х+х³-64
x + 6y = 20 /*(-3)
3x + 3y = 15
- 3x - 18y = - 60
3x + 3y = 15
---------------------------- +
- 15y = - 45
y = 3
x = 20 - 6y = 20 - 6*3 = 20 - 18 = 2
Ответ
(2; 3)