Note: a radioactive decay constant is always negative.
time = [natural log(ending amount / beginning amount)] / k
time = ln (20 / 24) / -.00011
time = ln (5/6) / -.00011
time = -.018232155683 / -.00011
time =
<span>
<span>
<span>
165.7468698455
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</span>
</span>
time =
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<span>
165.75 years
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Answer:
C
Step-by-step explanation:
Answer:
A. (2, -3).
Step-by-step explanation:
The first step is to complete the square on the terms in x and the terms in y:
x² - 4x +4 +y² +6y + 9 =4
= (x - 2)² - 4 + (y + 3)² - 9 + 4 + 9 = 4
= = (x - 2)² + (y + 3)² - 9 + 9 - 4 + 4 = 4
= (x - 2)² - (y + 3)² = 4.
So the centre is at (2, -3).