Math Problem Statement

Tentukan persamaan garis singgung pada kurva berikut: a. y = -x^2 - 6x + 3 di titik yang berabasis -2, b. y = x^2 + 4x - 5 di titik (2, -16), c. y = 4/x di titik (2, 2).

Solution

The question asks to find the equation of the tangent line to various curves at specific points. Let's go step-by-step for each part:

Part a: y=x26x+3y = -x^2 - 6x + 3 at x=2x = -2

To find the equation of the tangent line, we need the derivative of the function to get the slope at the point and then use the point-slope form of the line equation.

  1. Find the derivative: dydx=2x6\frac{dy}{dx} = -2x - 6

  2. Evaluate the derivative at x=2x = -2 to get the slope: dydxx=2=2(2)6=46=2\frac{dy}{dx} \bigg|_{x = -2} = -2(-2) - 6 = 4 - 6 = -2 So the slope at x=2x = -2 is 2-2.

  3. Find the corresponding yy-coordinate at x=2x = -2: y=(2)26(2)+3=4+12+3=11y = -(-2)^2 - 6(-2) + 3 = -4 + 12 + 3 = 11 The point is (2,11)(-2, 11).

  4. Use the point-slope form: yy1=m(xx1)y - y_1 = m(x - x_1) y11=2(x+2)y - 11 = -2(x + 2) y11=2x4y - 11 = -2x - 4 y=2x+7y = -2x + 7 The equation of the tangent line is y=2x+7y = -2x + 7.


Part b: y=x2+4x5y = x^2 + 4x - 5 at (2,16)(2, -16)

  1. Find the derivative: dydx=2x+4\frac{dy}{dx} = 2x + 4

  2. Evaluate the derivative at x=2x = 2: dydxx=2=2(2)+4=4+4=8\frac{dy}{dx} \bigg|_{x = 2} = 2(2) + 4 = 4 + 4 = 8 The slope at x=2x = 2 is 88.

  3. The point is already given as (2,16)(2, -16).

  4. Use the point-slope form: yy1=m(xx1)y - y_1 = m(x - x_1) y+16=8(x2)y + 16 = 8(x - 2) y+16=8x16y + 16 = 8x - 16 y=8x32y = 8x - 32 The equation of the tangent line is y=8x32y = 8x - 32.


Part c: y=4xy = \frac{4}{x} at (2,2)(2, 2)

  1. Find the derivative: dydx=4x2\frac{dy}{dx} = -\frac{4}{x^2}

  2. Evaluate the derivative at x=2x = 2: dydxx=2=422=44=1\frac{dy}{dx} \bigg|_{x = 2} = -\frac{4}{2^2} = -\frac{4}{4} = -1 The slope at x=2x = 2 is 1-1.

  3. The point is (2,2)(2, 2).

  4. Use the point-slope form: y2=1(x2)y - 2 = -1(x - 2) y2=x+2y - 2 = -x + 2 y=x+4y = -x + 4 The equation of the tangent line is y=x+4y = -x + 4.


Would you like further details on any of these steps, or do you have any specific questions?

Related questions:

  1. What is the general process for finding the equation of a tangent line?
  2. How do you differentiate a rational function like y=4xy = \frac{4}{x}?
  3. Why is the slope of a tangent line important in calculus?
  4. How does the point-slope form differ from the slope-intercept form of a line?
  5. What is the significance of second derivatives in understanding curves?

Tip: The point-slope form yy1=m(xx1)y - y_1 = m(x - x_1) is very useful when you have both a point and a slope—it allows quick derivation of the tangent line equation!

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Math Problem Analysis

Mathematical Concepts

Derivatives
Tangent Line
Point-Slope Form

Formulas

Derivative of a function f'(x)
Point-Slope Form: y - y1 = m(x - x1)
Slope Formula for Tangent Line: m = f'(x)

Theorems

Differentiation
Tangent Line Theorem

Suitable Grade Level

Grade 10-12