1. parallel lines have same slope
Answer:
475 mph
Step-by-step explanation:
Distance = rate × time
time = distance / rate
If x is the speed of the plane in still air:
2100 / (x + 25) = 1890 / (x − 25)
Cross multiply:
2100 (x − 25) = 1890 (x + 25)
Distribute and solve:
2100x − 52500 = 1890x + 47250
210x = 99750
x = 475
We know that
We can write an Arithmetic Sequence as a rule:
<span>an = a1 + d(n−1)</span>
where
<span>a1 = the first term
<span>d =the "common difference" between terms
in this problem
a1=15 a2=7 a3=-1 a4=-9 ..... an=-225
d=a2-a1
d=7-15-----> d=-8
</span></span>an = a1 + d(n−1)
for
an=-225
d=-8
a1=15
find n
-225=15+(-8)*(n-1)--> (n-1)=[-225-15]/-8----> n-1=30---> n=30+1---> n=31
the answer is31
Answer:
The correct answer is:
Between 600 and 700 years (B)
Step-by-step explanation:
At a constant decay rate, the half-life of a radioactive substance is the time taken for the substance to decay to half of its original mass. The formula for radioactive exponential decay is given by:

First, let us calculate the decay constant (k)

Next, let us calculate the half-life as follows:

Therefore the half-life is between 600 and 700 years
Answer:

Step-by-step explanation:
