Answer:
In statistics and econometrics, the first-difference (FD) estimator is an estimator used to address the problem of omitted variables with panel data. It is consistent under the assumptions of the fixed effects model. In certain situations it can be more efficient than the standard fixed effects (or "within") estimator.
First differences are the differences between consecutive y-‐values in tables of values with evenly spaced x-‐values. If the first differences of a relation are constant, the relation is _______________________________ If the first differences of a relation are not constant, the relation is ___________________________
Yes the commutative property of addition.
<span>Dr. Graham currently has two acid solutions.
60% acid AND 20% acid </span>
Dr. Graham needs 30 L of a 50% acid solution
We set up 2 equations in which s = 60% acid and t = 20% acid
A) s + t = 30
B) .60s + .20t = (.50 * 30)
We multiply equation A by -.20
A) = -.20s -.20t = -6 then we add it to B)
B) .60s + .20t = 15
.40s = 9
s = 22.5
t = 7.5
So, she needs to mix 22.5 liters of 60% acid with 7.5 liters of 20% acid.
Source:
http://1728.org/mixture.htm
Answer:
<em>-</em><em>1</em>
Step-by-step explanation:
<em>x</em><em> </em><em>is</em><em> </em><em>an</em><em> </em><em>unknown</em><em> </em><em>and</em><em> </em><em>can</em><em> </em><em>be</em><em> </em><em>known</em><em> </em><em>as</em><em> </em><em><u>1</u></em><em><u> </u></em><em>or</em><em> </em><em><u>-</u></em><em><u>1</u></em><em><u> </u></em><em>based</em><em> </em><em>on</em><em> </em><em>the</em><em> </em><em>circumstance</em><em>.</em><em> </em>
<em>Therefore</em><em>,</em><em> </em><em>in</em><em> </em><em>this</em><em> </em><em>case</em><em>,</em><em> </em><em>x</em><em> </em><em>is</em><em> </em><em>known</em><em> </em><em>as</em><em> </em><em><u>-</u></em><em><u>1</u></em>