They are right except for 12. i think it is C but i could be wrong.
Answer:
(x+11) by (x+10)
Step-by-step explanation:
We know that Area = Length x width
Given: Area = x²+9x+20
Lets sort this out first
Area = x²+5x + 4x + 20
Area = x(x+5) + 4(x+5)
Area = (x+5) (x+4)
Therefore, it is concluded that:
Length 'l' = (x+5) feet
Width 'w' = (x+4) feet
if a 3-foot walkway is built around the fountain, we'll add 3 feet on both sides
Therefore,
Outer Length = (x+5+3+3) = (x+11) feet
Outer Width = (x+4+3+3) = (x+10) feet
Answer:
The fountain is (x+5) by (x+4).
dimensions of the outside border of the walkway are (x+11) by (x+10)
12.5 kilometers per liter
The bones at the time they were discovered when the radioactive element carbon-14 has a half-life of total 5750 years are 10062.5-year-old.
<h3>What is half-lives?</h3>
Half lives is the time interval which is need to decay the atomic nuclei of a radioactive sample.
There is a scientist who determined that the bones from a mastodon had lost 70.3% of their carbon-14. Thus, the fraction remaining is,
f=1-(70.3/100)=1-0.703
f=1-(70.3/100)=0.297
Now the fraction remaining can be given as,
f=(1/2)ⁿ
Here, n is the half life elapsed. Put the value of fraction remaining.
0.297=(1/2)ⁿ
n=1.75
The radioactive element carbon-14 has a half-life of total 5750 years. Thus,
Years=1.75*5750
Years=10062.5
Thus, the bones at the time they were discovered when the radioactive element carbon-14 has a half-life of total 5750 years are 10062.5-year-old.
Learn more about the half lives here;
brainly.com/question/2320811
#SPJ1
