Answer:
Step-by-step explanation:
i is an imaginary unit, this means
Rewrite -5 as 
then
Rewrite -25 as 
then
Answer:
(n+54)/9 = 21
Step-by-step explanation:
A number: n
Is increased by 54: n+54
The sum is divided by 9: (n +54)/9
and the result is 21:
(n +54)/9 = 21
Answer:
2 cows and 5 chickens.
Step-by-step explanation:
NOTE: This will be solved using simultaneous equations.
Let x = cows and y = chickens
1. form two equations
4x + 2y = 18 ... (1)
x + y = 7 .... (2)
2. make y (or x) the subject of one equation
x + y = 7
y = 7 - x ... (3)
3. Substitute (3) into (1)
4x + 2( 7 - x) = 18
4. solve for x
4x + 14 - 2x = 18
2x = 4
x = 2
5. Now substitute x value into equation (2)
x + y = 7
2 + y = 7
y = 5
∴ cows (x) = 2
chickens (y) = 5
The local minimum of function is an argument x for which the first derivative of function g(x) is equal to zero, so:
g'(x)=0
g'(x)=(x^4-5x^2+4)'=4x^3-10x=0
x(4x^2-10)=0
x=0 or 4x^2-10=0
4x^2-10=0 /4
x^2-10/4=0
x^2-5/2=0
[x-sqrt(5/2)][x+sqrt(5/2)]=0
Now we have to check wchich argument gives the minimum value from x=0, x=sqrt(5/2) and x=-sqrt(5/2).
g(0)=4
g(sqrt(5/2))=25/4-5*5/2+4=4-25/4=-9/4
g(-sqrt(5/2))=-9/4
The answer is sqrt(5/2) and -sqrt(5/2).
