Haha, you first start off with adding 3 to both sides, cancelling the -3, and adding it to 9. you end up with 5x=12, in which you divide both sides by 5. you get 2 and 2/5 or 12/5! hope that helps :)
Firstly, understand prefixes :)
giga 1000000000
mega 1000000
kilo 1000
deci 0.1
centi 0.01
milli 0.001
micro 0.000001
nano 0.000000001
Answer:
Part A = the middle one
Part B = 4 days
Step-by-step explanation:
1,300 / 4 = 325
325 x 4 = 1,300
Answer:
the question is incomplete, so I looked for a similar one:
<em>After the release of radioactive material into the atmosphere from a nuclear power plant, the hay was contaminated by iodine 131 ( half-life, 8 days). If it is all right to feed the hay to cows when 10% of the iodine 131 remains, how long did the farmers need to wait to use this hay? </em>
iodine's half life (we are given x, we need to find b):
0.5A₀ = A₀eᵇˣ
x = 8 days
we eliminate A₀ from both sides
0.5 = eᵇ⁸
ln 0.5 = ln eᵇ⁸
-0.69315 = b8
b = -0.69315 / 8 = -0.08664
since the farmers need to wait until only 10% of the iodine remains (we already calculated b, now we need to find x):
0.1A₀ = A₀eᵇˣ
0.1 = eᵇˣ
ln 0.1 = bx
where b = -0.08664
x = ln 0.1 / -0.08664 = -2.302585 / -0.08664 = 26.58 days
