Equation of the Secant Line...2

Discussion in 'Calculus' started by nycmathguy, Mar 25, 2022.

  1. nycmathguy

    nycmathguy

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    Find the equation of the secant line given that
    x = 1 and x = 2.

    f(x) = x^2 - 4

    Evaluate f(x) at x = 1 and x = 2.

    f(1) = (1)^2 - 4

    f(1) = 1 - 4

    f(1) = -3

    One point is (1, -3).

    f(2) = (2)^2 - 4

    f(2) = 4 - 4

    f(2) = 0

    Another point is (2, 0).

    Use (1, -3) to form a linear equation.

    y = mx + b_1

    -3 = m(1) + b_1

    -3 = m + b_1

    -3 - m = b_1

    Use (2, 0) to form another linear equation.

    y = mx + b_2

    0 = m(2) + b_2

    0 = 2m + b_2

    0 - 2m = b_2

    -2m = b_2

    Now set b_1 = b_2 to find m.

    -m - 3 = -2m

    -3 = -2m + m

    - 3 = -m

    -3/-1 = m

    3 = m

    I now have y = 3x + b.

    Use (1, -3) or (2, 0) to find b.

    I will use (2, 0).

    y = 3x + b

    0 = 3(2) + b

    0 = 6 + b

    0 - 6 = m

    -6 = m. . .the slope of the secant line we seek.

    So, the equation of the secant line is y = 3x - 6.

    You say?
     
    nycmathguy, Mar 25, 2022
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    MathLover1 likes this.
  2. nycmathguy

    MathLover1

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    correct
     
    MathLover1, Mar 25, 2022
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    nycmathguy likes this.
  3. nycmathguy

    nycmathguy

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    I like it. I love it. I need more calculus.
     
    nycmathguy, Mar 26, 2022
    #3
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