Answer:
z = -12
Step-by-step explanation:
The given system of equations is:
xy/(x + y) = 1 ...........................(1)
xz/(x + z) = 2...........................(2)
yz/(y + z) = 3...........................(3)
From (1): x + y = xy
=> y = xy - x
y = x(y - 1)
x = y/(y - 1).......................................(4)
From (2): 2(x + z) = xz
=> 2x + 2z = xz
2x = xz - 2z
2x = z(x - 2)
z = 2x/(x - 2) ....................................(5)
From (3): 3(y + z) = yz
=> 3y + 3z = yz
3y = yz - 3z
3y = z(y - 3)
z = 3y/(y - 3)....................................(6)
Comparing (5) and (6)
2x/(x - 2) = 3y/(y - 3)
2x(y - 3) = 3y(x - 2)
2xy - 6x = 3xy - 6y
6(y - x) = xy .................................(7)
But from (1): xy = x + y
Using this in (7), we have
6(y - x) = x + y
6y - y - 6x - x = 0
5y - 7x = 0
5y = 7x
x = 5y/7................................................(8)
Using this in (4)
5y/7 = y/(y - 1)
1/(y - 1) = 5/7
(y - 1) = 7/5
y = 1 + 7/5
y = 12/5..........................................(9)
Using this in (8)
x = 5(12/5)/7 = 12/7 .......................(10)
Using (10) in (5)
z = 2x/(x - 2)
z = 2(12/7) ÷ (12/7 - 2)
= 24/7 ÷ -2/7
= 24/7 × (-7/2)
= -24/2 = -12
z = -12.
Think of this as (1/5)x - 4 = -75, where x is the number that we are trying to figure out. To figure this out, we want to get x by itself, so we can go:
(1/5)x=-71
x=-71*5
x=-355
So your number is -355
4+3.5=7.5
7.5x =180
180/7.5
=24 (answer)
<span>d.5,5,5,5. A prime number is a number only divisible by 1 and itself. 1 is not a prime number.</span>
Answer:
Prospective study
Step-by-step explanation:
<em>A cross-sectional study, also known as transverse study, is a type of observational study that analyzes data from a population at a specific point in time.</em> This kind of observation is used if cases cannot be identified a priori or if the prevalence of the disease or condition needs to be determined.
Cohort studies are when two or more groups of subjects are followed over time to see if they develop some disease or if some event occurs, there are two type of cohort studies, prospective and retrospective. <em>Prospective studies (or follow-up studies) follow subjects with different exposures until some point in time where something happens or the study ends</em>, r<em>etrospective studies use historical data</em> to make comparisons based on risk factors or exposures that occurred before the events.
Considering the information given and the observational study exposed to the question, we can conclude that we are talking about a prospective study because data is collected over the next 10 years.
I hope you find this information useful and interesting! Good luck!
