Finding the y-intercept value b

MathematicsLinear EquationsHard

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The table gives the coordinates of two points on a line in the $xy$-plane. The $y$-intercept of the line is $(k-5, b)$, where $k$ and $b$ are constants. What is the value of $b$?

This question includes visual content: A 2x3 table with headers 'x' and 'y'. The first row of data contains (k, 13) and the second row contains (k + 7, -15).

Animated Video Solution

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Step by Step Written Solution

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Step 1

Hi İzel, let's solve this problem together. We are given two points on a line and need to find the value of the constant b, which is related to the y-intercept.

Linear Coordinates Analysis

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Step 2

First, let's look at the two points provided in the table. We have the coordinate pairs k comma thirteen and k plus seven comma negative fifteen.

Points from table:

$$(x_1, y_1) = (k, 13)$$
$$(x_2, y_2) = (k + 7, -15)$$
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Step 3

To find the slope of the line, we use the formula rise over run, which is the change in y divided by the change in x.

$$m = \frac{y_2 - y_1}{x_2 - x_1}$$
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Step 4

Substituting our values in, the change in y is negative fifteen minus thirteen, and the change in x is the quantity k plus seven minus k.

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Step 5

Simplifying the denominator, the k values cancel out, leaving us with seven. In the numerator, negative fifteen minus thirteen is negative twenty-eight.

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Step 6

Finally, negative twenty-eight divided by seven gives us a slope of negative four.

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Step 7

Now, the problem states that the y-intercept of the line is the point k minus five comma b.

Analyzing the y-intercept

$$(k - 5, b)$$
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Step 8

By definition, the y-intercept occurs where the x-coordinate is zero. This means k minus five must equal zero.

$$k - 5 = 0$$
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Step 9

Solving for k, we add five to both sides and find that k equals five.

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Step 10

If k is five, we can find the actual coordinates of the points in our table. The first point p one was k comma thirteen, which becomes five comma thirteen.

$$P_1 = (5, 13)$$

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About This Question

Subject
Mathematics
Topic
Linear Equations
Difficulty
Hard
Question Type
Open Ended

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