Answer:
<em>Numbers: 6 and -2</em>
Step-by-step explanation:
<u>Equations</u>
This question can be solved by inspection. It's just a matter of factoring 12 into two factors that sum 4. Both numbers must be of different signs and they are 6 and -2. Their sum is indeed 6-2=4 and their product is 6*(-2)=-12.
However, we'll solve it by the use of equations. Let's call x and y to the numbers. They must comply:
![x+y=4\qquad\qquad [1]](https://tex.z-dn.net/?f=x%2By%3D4%5Cqquad%5Cqquad%20%5B1%5D)
![x.y=-12\qquad\qquad [2]](https://tex.z-dn.net/?f=x.y%3D-12%5Cqquad%5Cqquad%20%5B2%5D)
Solving [1] for y:
Substituting in [2]
Operating:
Rearranging:
Solving with the quadratic formula:
With a=1, b=-4, c=-12:
The solutions are:
This confirms the preliminary results.
Numbers: 6 and -2
I believe it is the commutative property, hope this helps!
If you would like to calculate the arithmetic mean, geometric mean, and harmonic mean from the following averages, you can calculate this using the following steps:
averages: 56.4, 59.8, 55.8
the number of values: 3
arithmetic mean:
(56.4 + 59.8 + 55.8) / 3 = 57.33
geometric mean:
(56.4 * 59.8 * 55.8)^(1/3) = 57.31
harmonic mean:
3 / (1/56.4 + 1/59.8 + 1/55.8) = 57.28
Answer:
Ellen invested $60 and Bob invested $140
Step-by-step explanation:
let the two amounts invested by 3x and 7x
(notice 3x : 7x = 3 : 7 )
then 3x + 7x = 200
10x = 200
x = 20
then 3x = 3(20) = 60
and 7x = 7(20) = 140
60+140=200
