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
F(x) = x² + x - 20 = x² + 5x - 4x - 20 = x(x + 5) - 4(x + 5) = (x + 5)(x - 4)
f(x) = 0 ⇔ (x + 5)(x - 4) = 0 ⇔ x + 5 = 0 or x - 4 = 0 ⇒ x = -5 or x = 4
Answer: C. x = -5 and x = 4.
You would use the formula for the specific term you wish to find;
The formula is:
a = starting value of the sequence
d = the common difference (i.e. the difference between any two consecutive terms of the sequence)
n = the value corresponding to the position of the desired term in the sequence (i.e. 1 is the first term, 2 is the second, etc.)
Un = the actual vaue of the the term
For example, if we have the arithmetic sequence:
2, 6, 10, 14, ...
And let's say we want to find the 62nd term;
Then:
a = 2
d = 4
(i.e. 6 - 2 = 4, 10 - 6 = 4, 14 - 10 = 4;
You should always get the same number no matter which two terms you find the difference between so long as they are both
consecutive [next to each other], otherwise you are not dealing with an arithmetic sequence)
n = 62
And so:
Answer:
80
Step-by-step explanation:
-|-x| = 7 is already wrong to begin with. The absolute value gives you the distance from zero so it is always positive. And the fact that if |-x| is always positive then -|-x| is always negative and you are equating it to a positive number.
