Math Problem Statement

can you explain how this person solved this step by step

Can you explain how this person solved this step by step?

Solution

Certainly! I'll walk you through each step of the solution in the image you provided. This is a detailed process for finding the slope (denoted by mm) of the secant line between two points on a curve.

Step-by-step Explanation:

  1. Given Points: The points provided are (4,56)(-4, 56) and (4+h,k(4+h))(-4 + h, k(-4 + h)). This indicates two points on the graph, with one point being fixed at (4,56)(-4, 56) and the other point shifting based on the variable hh.

  2. Slope Formula: The slope mm is calculated as: m=k(4+h)56(4+h)(4)m = \frac{k(-4+h) - 56}{(-4+h) - (-4)} This is the standard slope formula m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}, where the second point is (4+h,k(4+h))(-4+h, k(-4+h)) and the first point is (4,56)(-4, 56).

  3. Simplifying the Denominator: The denominator simplifies as: (4+h)(4)=h(-4+h) - (-4) = h So the slope equation becomes: m=k(4+h)56hm = \frac{k(-4+h) - 56}{h}

  4. Substituting the Function k(x)k(x): Based on the problem setup, k(x)=4x2+2xk(x) = 4x^2 + 2x. So, for k(4+h)k(-4+h), we substitute into this function: k(4+h)=4(4+h)2+2(4+h)k(-4+h) = 4(-4+h)^2 + 2(-4+h)

  5. Expanding the Expression k(4+h)k(-4+h): First, expand (4+h)2(-4+h)^2: (4+h)2=168h+h2(-4+h)^2 = 16 - 8h + h^2 Now, substitute this into the function k(4+h)k(-4+h): k(4+h)=4(168h+h2)+2(4+h)k(-4+h) = 4(16 - 8h + h^2) + 2(-4+h) Simplify the terms: k(4+h)=6432h+4h28+2h=5630h+4h2k(-4+h) = 64 - 32h + 4h^2 - 8 + 2h = 56 - 30h + 4h^2

  6. Substituting Back into the Slope Formula: Now, substitute k(4+h)=5630h+4h2k(-4+h) = 56 - 30h + 4h^2 into the slope formula: m=(5630h+4h2)56hm = \frac{(56 - 30h + 4h^2) - 56}{h} This simplifies to: m=30h+4h2hm = \frac{-30h + 4h^2}{h}

  7. Simplifying the Slope Expression: Factor out hh from the numerator: m=h(30+4h)hm = \frac{h(-30 + 4h)}{h} The hh's cancel out: m=30+4hm = -30 + 4h

Thus, the final expression for the slope mm is: m=30+4hm = -30 + 4h

Summary of Steps:

  1. Start with two points (4,56)(-4, 56) and (4+h,k(4+h))(-4+h, k(-4+h)).
  2. Use the slope formula m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}.
  3. Simplify the denominator to hh.
  4. Substitute the function k(x)=4x2+2xk(x) = 4x^2 + 2x and expand for k(4+h)k(-4+h).
  5. Simplify and factor the expression.
  6. Cancel out hh to get the final slope.

Do you want more details on any of these steps, or do you have any questions?

Here are five related questions:

  1. What is the geometric meaning of the slope of a secant line?
  2. How would this process change if the function k(x)k(x) were different?
  3. What is the limit of the slope mm as h0h \to 0?
  4. How does this process relate to the concept of the derivative?
  5. Can this method be applied to find the slope of a tangent line?

Tip: When simplifying algebraic expressions, be careful to expand and combine like terms correctly before factoring.

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Math Problem Analysis

Mathematical Concepts

Algebra
Slope of a secant line
Quadratic Functions

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Quadratic function expansion: (a + b)^2 = a^2 + 2ab + b^2

Theorems

Slope of a secant line between two points on a curve
Polynomial simplification techniques

Suitable Grade Level

Grade 11-12 (Advanced Algebra/Precalculus)