5/7 which means for every 7 kids, one owns a dog
5x-8y=1...(1)
3x+6y=-21...(2)
(1)*3:
15x-24y=3...(3)
(2)*5:
15x+30y=-105...(2)
(3)-(2):
15x-24y-(15x+30y)=3-(-105)
15x-24y-15x-30y=108
-54y=108
y=-2
We would need a sample size of 560.
We first calculate the z-score associated. with this level of confidence:
Convert 95% to a decimal: 95% = 95/100 = 0.95
Subtract from 1: 1-0.95 = 0.05
Divide by 2: 0.05/2 = 0.025
Subtract from 1: 1-0.025 = 0.975
Using a z-table (http://www.z-table.com) we see that this is associated with a z-score of 1.96.
The margin of error, ME, is given by:
We want ME to be 4%; 4% = 4/100 = 0.04. Substituting this into our equation, as well as our proportion and z-score,
we are given
x^2-4x-5
we can use formula
x^2-(a+b)x+ab=(x-a)(x-b)
so, we have
a+b=4
ab=-5
now, we can solve for a and b
and we get
a=5, b=-1
now, we can plug it in formula
x^2-4x-5=(x-5)(x+1) ............Answer