Linear Equations, Slope-Intercept Form, and Graphing Techniques

Theoretical Foundations of Slope-Intercept Form

  • The slope-intercept form of a linear equation is algebraically expressed as:   y=mx+by = mx + b

  • Variable definitions:

    • yy: Dependent variable representing the vertical coordinate.

    • xx: Independent variable representing the horizontal coordinate.

    • mm: The slope of the line, defining the rate of change and the ratio of vertical change to horizontal change (riserun\frac{\text{rise}}{\text{run}}).

    • bb: The yy-intercept, defining the point (0,b)\left(0, b\right) where the line crosses the vertical yy-axis.

Matching Linear Equations to Corresponding Lines

  • Line A:

    • Base equation: y=2+xy = 2 + x

    • Standard slope-intercept rearrangement: y=x+2y = x + 2

    • Identified slope: m=1m = 1

    • Identified yy-intercept: b=2b = 2

  • Line B:

    • Base equation: y=−4+2xy = -4 + 2x

    • Standard slope-intercept rearrangement: y=2x−4y = 2x - 4

    • Identified slope: m=2m = 2

    • Identified yy-intercept: b=−4b = -4

    • Transcription variant noted: X 2−4+2xX\,2 - 4 + 2x

  • Line C:

    • Base equation: y=3−xy = 3 - x

    • Standard slope-intercept rearrangement: y=−x+3y = -x + 3

    • Identified slope: m=−1m = -1

    • Identified yy-intercept: b=3b = 3

    • Transcription variant noted: 8=3−X8 = 3 - X

Converting Equations to Slope-Intercept Form and Identifying Slope

  • Problem 34:

    • Given equation: y=−3x+10y = -3x + 10

    • Current format: Already in standard slope-intercept form (y=mx+by = mx + b)

    • Identified slope: m=−3m = -3

    • Identified yy-intercept: b=10b = 10

    • Evaluation status: Confirmed correct ("good")

  • Problem 33:

    • Given equation in standard form: 5x+3y=155x + 3y = 15

    • Step 1 (Isolate the variable term containing yy by subtracting 5x5x from both sides):     5x−5x+3y=−5x+155x - 5x + 3y = -5x + 15     3y=−5x+153y = -5x + 15

    • Step 2 (Divide every term on both sides by the coefficient 33):     3y3=−5x3+153\frac{3y}{3} = \frac{-5x}{3} + \frac{15}{3}     y=−53x+5y = -\frac{5}{3}x + 5

    • Identified slope: m=−53m = -\frac{5}{3}

    • Identified yy-intercept: b=5b = 5

  • Problem 37:

    • Given equation: 2y=x+122y = x + 12

    • Step 1 (Isolate yy by dividing each term by 22):     2y2=12x+122\frac{2y}{2} = \frac{1}{2}x + \frac{12}{2}     y=12x+6y = \frac{1}{2}x + 6

    • Identified slope: m=12m = \frac{1}{2}

    • Identified yy-intercept: b=6b = 6

  • Additional Linear Form (7x−8=y7x - 8 = y):

    • Given equation: 7x−8=y7x - 8 = y

    • Algebraic manipulation notes: −7x−7x-7x - 7x, yielding −8=−7x+y-8 = -7x + y or rewritten as −8=−7x−4-8 = -7x - 4

    • Symmetric property rearrangement to standard slope-intercept form:     y=7x−8y = 7x - 8

    • Identified slope: m=7m = 7

    • Identified yy-intercept: b=−8b = -8

Graphing Lines Given Linear Equations

  • Problem 34 (Graphing):

    • Equation: y=−x−5y = -x - 5

    • Slope: m=−1=−11m = -1 = -\frac{1}{1}

    • yy-intercept: b=−5b = -5, corresponding to coordinate point (0,−5)\left(0, -5\right)

    • Graphing trajectory: From (0,−5)\left(0, -5\right), move down 11 unit and right 11 unit (or up 11 unit and left 11 unit)

  • Problem 35:

    • Equation: y=2x+8y = 2x + 8

    • Slope: m=2=21m = 2 = \frac{2}{1}

    • yy-intercept: b=8b = 8, corresponding to coordinate point (0,8)\left(0, 8\right)

    • Graphing trajectory: From (0,8)\left(0, 8\right), move up 22 units and right 11 unit (or down 22 units and left 11 unit)

    • Evaluation status: Confirmed correct ("good")

  • Problem 38:

    • Given equation: −2x+2y=−8-2x + 2y = -8

    • Step 1 (Add 2x2x to both sides of the equation):     −2x+2x+2y=2x−8-2x + 2x + 2y = 2x - 8     2y=2x−82y = 2x - 8

    • Step 2 (Divide every term by 22):     2y2=2x2−82\frac{2y}{2} = \frac{2x}{2} - \frac{8}{2}     y=1x−4y = 1x - 4     y=x−4y = x - 4

    • Identified slope: m=1=11m = 1 = \frac{1}{1}

    • Identified yy-intercept: b=−4b = -4, corresponding to coordinate point (0,−4)\left(0, -4\right)

  • Problem 40:

    • Equation: y=−2x+4y = -2x + 4

    • Slope: m=−2=−21m = -2 = -\frac{2}{1}

    • yy-intercept: b=4b = 4, corresponding to coordinate point (0,4)\left(0, 4\right)

    • Graphing trajectory: From (0,4)\left(0, 4\right), move down 22 units and right 11 unit

Coordinate Plane Values and Grid Reference Markings

  • Negative scale markers present on the Cartesian grid axes:

    • −8-8, −5-5, −4-4, −3-3, −2-2, −1-1

  • Neutral origin marker:

    • 00

  • Positive scale markers present on the Cartesian grid axes:

    • 11, 22, 33, 44, 55, 66, 77

  • Additional raw numerical annotations and coordinate references recorded:

    • Sequence: 7,7,7,7,4,13,3,9,5577, 7, 7, 7, 4, 13, 3, 9, 557

    • Value: 70547054

    • Incremental coordinate runs: 1,2,3,4,5,6,71, 2, 3, 4, 5, 6, 7 and −8,−5,−4,−3,−2-8, -5, -4, -3, -2

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