13/12: (31/18 - 23/9) = 13/12 * (-18/15 ) = 13/10 =1,3
1) ( X - 7)^2 = X^2 - 14X + 49
2) 2 * ( X - 7)*( X + 7) = 2 * ( X^2 - 49) = 2X^2 - 98
3) ( X + 7)^2 = X^2 + 14X + 49
...............................................
X^2 - 14X + 49 - 2X^2 + 98 + X^2 + 14X + 49 = 49 + 98 + 49 = 196
ОТВЕТ 196
Y(x)= x⁴-4x³-8x²+13
y'(x)=(x⁴-4x³-8x²+13)' = 4x³-12x²-16x
(25,243+17,77)-2,77= 43.013-2.77=40.243
СМОТРИ, а так можно?
4/2=18/9