Answer:
For First Solution: 
is the solution of equation y''-y=0.
For 2nd Solution:
is the solution of equation y''-y=0.
Step-by-step explanation:
For First Solution: 
In order to prove whether it is a solution or not we have to put it into the equation and check. For this we have to take derivatives.

First order derivative:

2nd order Derivative:

Put Them in equation y''-y=0
e^t-e^t=0
0=0
Hence
is the solution of equation y''-y=0.
For 2nd Solution:

In order to prove whether it is a solution or not we have to put it into the equation and check. For this we have to take derivatives.

First order derivative:

2nd order Derivative:

Put Them in equation y''-y=0
cosht-cosht=0
0=0
Hence
is the solution of equation y''-y=0.
Answer:
Option E) 61.6
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 100 bushels per acre
Standard Deviation, σ = 30 bushels per acre
We assume that the distribution of yield is a bell shaped distribution that is a normal distribution.
Formula:

P(X>x) = 0.90
We have to find the value of x such that the probability is 0.90
P(X > x)
Calculation the value from standard normal table, we have,

Hence, the yield of 61.6 bushels per acre or more would save the seed.
Answer:
The answer of the following question is m = \frac{C - b - bt}{r + rt}.
Solution:
C = (b + rm)(1 + t),
C = b + rm + bt + rmt
C = b + bt + rm + rmt
C - b - bt = m (r + rt)
\frac{C - b - bt}{r + rt} = m
t\neq -1,
r\neq 0