18,4 км = 1840000 см
1840000 : 400000 = 4,6 (см) - расстояние между селами на карте.
Ответ: 4,6 см.
Possible derivation:
d/dx(y) = d/dx(1/2 cos(2 x)-x)
The derivative of y is zero:
0 = d/dx(-x+1/2 cos(2 x))
Differentiate the sum term by term and factor out constants:
0 = (d/dx(cos(2 x)))/2-d/dx(x)
The derivative of x is 1:
0 = 1/2 (d/dx(cos(2 x)))-1
Using the chain rule, d/dx(cos(2 x)) = ( dcos(u))/( du) ( du)/( dx), where u = 2 x and ( d)/( du)(cos(u)) = -sin(u):
0 = -1+1/2-d/dx(2 x) sin(2 x)
Factor out constants:
0 = -1-1/2 sin(2 x) 2 d/dx(x)
Simplify the expression:
0 = -1-(d/dx(x)) sin(2 x)
The derivative of x is 1:
Answer: |
| 0 = -1-1 sin(2 x)
D^2 - c^2 = (1/2)^2 - 2^2 = 1/4 - 4 = -3.75
64^3 - 8^5 - 4^7 = ( 2^6 )^3 - ( 2^3 )^5 - (2^2 )^7 = 2^18 - 2^15 - 2^14 =
= 2^14 * ( 2^4 - 2 - 1 ) = 2^14 * ( 16 - 3 ) = 2^14 * 13
Пусть x²-8=t, тогда получаем уравнение t²+7t-8=0. Дискриминант D=7²-4*1*(-8)=81=9², t1=(-7+9)/2=1, t2=(-7-9)/2=-8. Решая уравнение x²-8=1, находим x1=3, x2=-3. Решая уравнение x²-8=-8, находим x3=x4=0