20 : 0.75 = 40 : 1.5 = 80 : 3
X = girls
Y = boys
X + y = 428
Answer:
1/19
Step-by-step explanation:
Answer: -0.25
Explanation:
We assume you want to find the inverse transform of s/(s^2 +3s -4). This can be written in partial fraction form as
(4/5)/(s+4) + (1/5)/(s-1)
which can be found in a table of transforms to be the transform of
(4/5)e^(-4t) + (1/5)e^t
_____
There are a number of ways to determine the partial fractions. They all start with factoring the denominator.
s^2 +3x -4 = (s+4)(s-1)
After that, you can postulate the final form and determine the values of the coefficients that make it so. For example:
A/(s+4) + B/(s-1) = ((A+B)s + (4B-A))/(s^2 +3x -4)
This gives rise to two equations:
(A+B) = 1
(4B-A) = 0
