Answer:
The expression that represents the number of days until only 10% remains is T((d) 10 %) =100×
.
Step-by-step explanation:
The equation for half life is of the form
A = A₀×
.........................................................................(1)
Where
A = Final amount
A₀ = Initial amount
t = Time
h = Half life
For the equation T(d) = 100×2⁽⁻²⁾....................................(2)
We have by comparison with the equation for half life
2 ≡ 
and and the equation (2) can be written as
Percentage remaining after 2 half lives is
×100=100×
However if the half life of Technetium-99m is 6 hours then we have for one day
×100=100×
Therefore an expression that represents the number of days until only 10% remains is
×100=100×
= 10 %
=
= ㏑ = ㏑()
= 
×㏑
= ㏑()
= 
= 3.322
Therefore the expression for the number of days 10 % of Technetium-99m will be remaining is
T((d) 10 %) =100×
Answer:
The equation is y=1/5x-4.
Step-by-step explanation:
You substitute the slope and the y-intercept, which is 1/5 and -4, and plug them into the y=mx+b equation.
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a product of a number and -2 increased by 8 is -4. what is the number?
a product of a number and -2 increased by 8 is -4. what is the number?
10/14/2014 | Alvin from Plano, TX | 1 Answer | 0 Votes
Geometry
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1 ANSWER
Nathan B.
Sacramento, CA
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A product means multiplication, so...
(x * -2) +8 = -4
-2x + 8 = -4
To isolate the x, we have a couple of different ways, but the easier for now would be to start off by moving the 8 to the other side via subtracting both sides by 8:
-2x + 8 - 8 = -4 - 8
-2x = -12
Next, we divide both sides by -2
-2x / -2 = -12 / -2
x = 6
Answer:
Step-by-step explanation:
can u be more specific
Each girl started with 15 dollars.
4$ is the ending amount
x= the amount of money each girl received
4= 2x - 2(13)
Since there were two girls who both received x amount of money, x is multiplied by two. Since both the girls spent 13 dolars on lunch, their original amount is subtracted by 13 times two, since there are two lunches being bought. The end amount of money is four.
to solve:
4= 2x - 2(13)
4= 2x - 26 Simplify by combining like terms
30= 2x Isolate the variable by adding 26 to both sides
15=x Continue to isolate the variable by dividing both sides by two
Each girl started with 15 dolars. Each girl spent thirteen dolars on lunch and had two dolars left over. Each girls' two dolars left over adds up to four dollars.
