She made a mistake in steps 3-4
The half life of the radioactive isotope to the nearest tenth is 0.83 days.
<h3>What is rate of radioactive decay?</h3>
The rate of radioactive decay is the rate at which a radioactive isotope is disintegrated. The half life is the time taken for half of the original amount of radioactive isotope to remain.
Given that;
t/12 = 0.693/k
Where;
t1/2 - half life
k =decay constant
t/12 = 0.693/0.84
t/12 = 0.83 days
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The value of x from the expression is 2
<h3>Expression and equation </h3>
Given the expression
2x = 74/2 - 37
We are to calculate the value of x from the expression
2x = 37 - 37
Since 37 - 37 = 0
2x = 0
Divide both sides by 2:
2x/2 = 0/2
x = 0
Hence the value of x from the expression is 2
Learn more on expression here: brainly.com/question/22048677
Answer:
C
Step-by-step explanation:
12^2 = 144, 9^2 = 81, and 15^2 = 225.
144 + 81 = 225, therefore a^2 + b^2 = c^2.