В1.
с=(x-1)(x-2) - (x-1)(x-5) + (x-5)(x-2) =
12 3 4
= x²-x-2x+2-4(x²-x-5x+5)+3(x²-5x-2x+10) =
12
= x²-3x+2-4(x²-6x+5)+3(x²-7x+10)=
12
=x²-3x+2-4x²+24x-20+3x²-21x+30 =
12
= 12/12 = 1
c² +2 = 1² +2 =3
Ответ: 3.
В2. х/у=5
х=5у
(x+y)² = (5y+y)² = (6y)² = 36y² = 36/5 = 7.2
xy 5y*y 5y² 5y²
Ответ: 7,2