<span>Ending Amt = Bgng Amt * e ^-0.03t
In this equation, the "-0.03" is the decay factor or "k"
We can now solve for half-life by this equation:
</span>t = <span>(<span>ln [y(t) ÷ a]<span>)<span> ÷ -k  (we can say beginning amount = 200 and ending amount = 100
</span></span></span></span>t = <span>(<span>ln [200 ÷ 100]<span>)<span> ÷ -k
</span></span></span></span>t = <span>(<span>ln [2]<span>)<span> ÷ -k
</span></span></span></span>t = 0.69314718056<span> ÷ --.03
t =</span><span><span><span> 23.1049060187
</span>
about 23 years
</span></span>
        
                    
             
        
        
        
If the width is w and the length is l, then 2w-2=l and 2w+2l=72 (using the perimeter equation). Plugging 2w-2 in for l, we get 2w+(2w-2)*2=72 and 6w-4=72. Adding 4 to both sides, we get 6w=76. After that, we divide both sides by 6 to get 74/6=w. Since l=2w-2=136/6, we get (136/6)(74/6)=656.75=area
        
             
        
        
        
Y = 925/z
hope this helps!
        
             
        
        
        
Answer:
To find the domains you must graph this equation and find the x-coordinates of the points plotted. That's the domain. 
Remember, if two points have the same x-coordinate then do not repeat the number when stating the domain. Domain also always must be written in the least to greatest order. Domains must be written with {} enclosing them. 
So if the x-coordinates were 4,5,6,4,7,5
You would write the domain as {4,5,6,7}