Answer:
B
Step-by-step explanation:
We are given that <em>x</em> and <em>y</em> are functions of time <em>t</em> such that <em>x</em> and <em>y</em> is a constant. So, we can write the following equation:

The rate of change of <em>x</em> and the rate of change of <em>y</em> with respect to time <em>t</em> is simply dx/dt and dy/dt, respectively. So, we will differentiate both sides with respect to <em>t: </em>
<em />
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Remember that the derivative of a constant is always 0. Therefore:

And by subtracting dy/dt from both sides, we acquire:

Hence, our answer is B.
Answer:
They give evidence of cultural, religious, or social characteristics of the people
Answer:
x = -1 and x = 4
Step-by-step explanation:
Step 1: Get everything to one side of the equation so it's set equal to zero..
-x² + 4x = x - 4 becomes...
-x² + 3x + 4 = 0 (subtract x and add 4 to both sides)
x² - 3x - 4 = 0 (divide both sides by -1, we want the x² term to be positive)
(x - 4)(x + 1) = 0 (factor)
so
x - 4 = 0, then x = 4
and
x + 1 = 0, then x = -1