Пять шестых!!!!!!!!!!!!!!!!!........!!.!!!...
1)7+4=11(лет)-корове и овце
2)11-9=2(года)-барану
Ответ:2года
2x + 3 = x - 6
2x - x = -6 - 3
x = -9
z + 4 - 3 = 2z
z - 2z = 3 - 4
-z = -1
z = 1
5 - 3y = 4 - 2y
-3y + 2y = 4 - 5
-y = -1
y = 1
7 - 3x = 4x - 9
-3x - 4x = -9 - 7
-7x = -16
7x = 16
x = 16/7
6a - 1 = 3a + 7
6a - 3a = 7 + 1
3a = 8
a = 8/3
10y - 3 = 5 + 3y
10y - 3y = 5 + 3
7y = 8
y = 8/7
У²-х²-у³+х³=
=(у²-х²) -1(у³-х³) = (у-х)(у+х) - (у-х)(у²+ху+х²)=
=(у-х)(у+х-(у²+ху+х²)) =(у-х)(-х²+х-ху-у²+у)
или
= -(х²-у²) +(х³-у³) = -(х-у)(х+у) +(х-у)(х²+ху +у²) =
=(х-у)(х²+ху +у²- (х+у)) = (х-у)(х²-х+ху+у²-у)