3. A curve has a slope of \( -x + 2 \) at each point \( (x, y) \) on the curve. Which of the following is an equation for this curve if it passes through the point \( (2, 1) \)?






Answer is: option3

\( -\frac{1}{2}x^2 + 2x - 1 \)

Solution:

We are given:

  1. The slope of the curve at each point \( (x, y) \) is \( -x + 2 \), meaning the derivative of the function \( f(x) \) is:

\[ f'(x) = -x + 2 \]

  1. The curve passes through the point \( (2, 1) \), which gives us the initial condition \( f(2) = 1 \).

\[ f(x) = \int (-x + 2)\, dx = -\frac{1}{2}x^2 + 2x + C \]

Use the point \( (2, 1) \) to solve for \( C \)

\[ 1 = -\frac{1}{2}(2)^2 + 2(2) + C \]

\[ 1 = -2 + 4 + C \]

\[ 1 = 2 + C \Rightarrow C = -1 \]

So, the equation of the curve is:

\[ f(x) = -\frac{1}{2}x^2 + 2x - 1 \]

This matches option (C).

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