Linear Functions: Standard Form

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Questions and Answers

Which of the following equations is in standard linear form?

  • xy + z = 5
  • $Ax + By = C$ (correct)
  • $4x^2 + y = 9$
  • $y = mx + b$

Which equation is NOT a linear equation?

  • x = 5
  • $y = 3x - 2$
  • 2x + 3y = 7
  • $x^2 + y = 4$ (correct)

Which of the following equations can be rearranged into standard linear form?

  • y = 7x + 9 (correct)
  • y = 4/x
  • y = $\sqrt{x}$ - 2
  • y = $x^3$ + 1

Which statement accurately explains why $y = x^2 + 1$ is not a linear equation?

<p>The variable <em>x</em> is squared. (B)</p> Signup and view all the answers

What is the slope of the line defined by the equation x = 8?

<p>Undefined (C)</p> Signup and view all the answers

What are the values of A, B, and C in the standard form of the linear equation -5x + 2y = 3?

<p>A = -5, B = 2, C = 3 (D)</p> Signup and view all the answers

Determine which of the following equations is linear.

<p>y = 7x - 3 (A)</p> Signup and view all the answers

Which of the following represents a linear equation when graphed?

<p>A straight line (C)</p> Signup and view all the answers

What is the x-intercept of the linear equation 4x + 3y = 12?

<p>(3, 0) (A)</p> Signup and view all the answers

What is the y-intercept of the linear equation 2x - 5y = 10?

<p>(0, -2) (A)</p> Signup and view all the answers

Given the equation y = -2, what is the y-intercept?

<p>(0, -2) (D)</p> Signup and view all the answers

What is the x-intercept of the equation x = 4?

<p>(4, 0) (B)</p> Signup and view all the answers

If a line is represented by the equation y = 5x + 3, where does the line intersect the y-axis?

<p>(0, 3) (C)</p> Signup and view all the answers

Given the linear equation y = 8x - 2, find the x-intercept.

<p>(1/4, 0) (B)</p> Signup and view all the answers

For the linear equation 6x - 3y = -18, determine the y-intercept.

<p>(0, 6) (D)</p> Signup and view all the answers

What is the y-intercept for the equation -3x + 5y = 9?

<p>(0, 9/5) (C)</p> Signup and view all the answers

Given the equation -2x - 3y = 10, what is the x-intercept?

<p>(-5, 0) (D)</p> Signup and view all the answers

What is the significance of the y-intercept of a linear function in a real-world context?

<p>It shows the starting point or initial value. (C)</p> Signup and view all the answers

How does multiplying a linear equation by a constant affect its graph?

<p>It does not change the graph. (D)</p> Signup and view all the answers

How can you determine if two linear equations have the same graph?

<p>If one equation is a multiple of the other. (C)</p> Signup and view all the answers

Which of the following statements is true about the graph of a linear equation with a positive slope?

<p>The line goes upwards from left to right (A)</p> Signup and view all the answers

Which of the following is the standard form of the equation y = 5x - 3 after it has been rearranged?

<p>-5x + y = -3 (A)</p> Signup and view all the answers

Which of the following statements about a vertical line is correct?

<p>Its slope is undefined (B)</p> Signup and view all the answers

Identify which of these is needed to uniquely define any straight line on a 2D plane:

<p>Two points (B)</p> Signup and view all the answers

How does changing the value of 'C' in the standard form of a linear equation (Ax + By = C) affect its graph?

<p>It shifts the line parallel to itself (D)</p> Signup and view all the answers

A linear equation has the form y=mx+c. If m=0, what is the result?

<p>The line is horizontal (D)</p> Signup and view all the answers

Which of the following is true about the x-intercept of a linear equation?

<p>The y-value is always 0. (A)</p> Signup and view all the answers

What adjustments must be made to correctly convert the equation $y = \frac{1}{3}x + 5$ into general form?

<p>Multiply all the terms by 3 (D)</p> Signup and view all the answers

How does increasing the value of the coefficient $A$ in the standard form of a linear equation $Ax + By = C$ affect the line's steepness, assuming $B$ and $C$ remain unchanged and $A$ is positive?

<p>It makes the line steeper (C)</p> Signup and view all the answers

What characteristic do nonlinear equations possess that distinguishes them from linear equations?

<p>They do not have a constant rate of change (C)</p> Signup and view all the answers

Which point represents the y-intercept of the linear equation $5x - 3y = 15$?

<p>$(0, -5)$ (B)</p> Signup and view all the answers

Considering a linear equation in standard form, how would the graph of $Ax + By = C$ change if $C$ were replaced with $C + k$ (where $k$ is a non-zero constant), assuming $A$ and $B$ remain unchanged?

<p>The line would shift vertically (D)</p> Signup and view all the answers

If the x-intercept of a linear equation is $(a, 0)$ and the y-intercept is $(0, b)$, what will the equation of the line be?

<p>$\frac{x}{a} + \frac{y}{b} = 1$ (B)</p> Signup and view all the answers

If a straight line has intercepts where $x$=6 and $y$=-3, what linear equation represents the same line?

<p>$x + 2y = 6$ (C)</p> Signup and view all the answers

Suppose a line's equation is $y = -5$. Which of the following points does not lie on this line?

<p>$(5, 5)$ (B)</p> Signup and view all the answers

Given that a line passes through the point $(0, b)$ and $(a, 0)$, what are its x- and y-intercept respectively?

<p>$(a, 0)$ and $(0, b)$ (C)</p> Signup and view all the answers

Given a linear function where if $x$ is 3, then $y$ is 5, and if $x$ is 6, then $y$ is 11, what is y when $x$ is 9?

<p>17 (D)</p> Signup and view all the answers

Flashcards

Linear Equation

A linear equation is an equation of a line.

Standard form of a Linear Equation

The standard form is Ax + By = C, where A, B, and C are constants.

X-intercept

The point where the graph of an equation intersects the x-axis.

Y-intercept

The point where the graph of an equation intersects the y-axis.

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Finding the x-intercept

Replace 'y' with 0 and solve for 'x'.

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Finding the y-intercept

Replace 'x' with 0 and solve for 'y'.

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Defining the y intercept

The y-intercept is the point at which the graph crosses the y-axis.

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Defining the x intercept

The x-intercept is the point at which the graph crosses the x-axis.

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Study Notes

Linear Programming and Functions

  • The lecture covers linear programming and linear functions.

Issues

  • Timetable for lectures are Mondays and Wednesdays from 4:15pm to 5:55pm.
  • Tutorials will be the following week.
  • Lecture material, including the booklet, are available on the Blackboard.
  • Class representatives will be chosen on Wednesday.

Content Overview

  • Focus is on linear functions.
  • Topics include standard form, graphing, and methods to find equations of graphed functions.

Standard Form

  • A linear equation represents a line.
  • The standard form of a linear equation is Ax + By = C.

Examples: Linear Equations/Functions

  • 2x + 4y = 8
  • 6y = 3 - x
  • x = 1
  • -2a + b = 5
  • (4x - y) / 3 = -7

Examples: Nonlinear Equations

  • 4x² + y = 5 (exponent is 2)
  • √x = 4 (contains a radical)
  • xy + x = 5 (variables are multiplied)
  • s/r + r = 3 (variables are divided)
  • These equations cannot be written in the standard form of Ax + By = C.

Determining Standard Form

  • Start with equation y = 5 - 2x
  • Rewrite it as 2x + y = 5
  • Where A = 2, B = 1, and C = 5 to confirm it is a linear equation.
  • For 2xy - 5y = 6, the term 2xy contains two variables
  • The equation cannot be put in standard form and is therefore not a linear equation.
  • For y = x² + 3, x is raised to the second power
  • The equation cannot be written in standard form and is therefore not a linear equation.
  • Start with y = 6 - 3x
  • Rewrite it as 3x + y = 6
  • Where A = 3, B = 1, C = 6 to confirm it is a linear equation.
  • Considering (1/4)x + 5y = 3
  • Multiply everything by 4 to eliminate the fraction
  • Which simplifies to x + 20y = 12
  • Where A = 1, B = 20, and C = 12 to confirm it is a linear equation.
  • -4x+7=2 (Determine whether the equation is a linear equation, if so write it in standard form.)

X and Y Intercepts

  • The x-intercept is the x-coordinate where the graph crosses the x-axis.
  • The y-intercept is the y-coordinate where the graph crosses the y-axis.

Graphing Equations

  • To graph 3x + 2y = 9, find the x and y intercepts.
  • Set y = 0 to find the x-intercept: 3x + 2(0) = 9, so x = 3.
  • Set x = 0 to find the y-intercept: 3(0) + 2y = 9, so y = 4.5.
  • Plot these points, (3,0) and (0, 4.5), then connect to draw the line.
  • To graph 2x + y = 4, find the x and y intercepts
  • Set y = 0 to find the x-intercept: 2x + (0) = 4, so x = 2.
  • Set x = 0 to find the y-intercept: 2(0) + y = 4, so y = 4.
  • Plot these points, (2,0) and (0,4), then connect to draw the line.

Finding X and Y Intercepts Examples

  • For x = 4y - 5, find x and y intercepts
  • To find the x-intercept, set y = 0 to get x = -5 with coordinates (-5, 0).
  • To find the y-intercept, set x = 0 to get y =5/4 with coordinates (0, 5/4).
  • For g(x) = -3x - 1, find x and y intercepts
  • To find the x-intercept, set g(x) = 0, solve for x: (-1/3, 0).
  • To find the y-intercept, set x = 0, solve for g(x): (0, -1).
  • For 6x - 3y = -18, find x and y intercepts
  • To find the x-intercept, set y = 0 and solve for x, resulting in x = -3, giving the point (-3, 0).
  • To find the y-intercept, set x = 0 and solve for y, resulting in y = 6, giving the point (0, 6).
  • For x = 3, find x and y intercepts
  • There is no y in the equation, the line is vertical and always equal to 3
  • The x-intercept is (3, 0).
  • There is no y-intercept as the line never crosses the y-axis.
  • For y = -2, find x and y intercepts
  • There is no x in the equation, the line is horizontal, and y is always equal to -2.
  • There is no x-intercept as the line never crosses the x-axis.
  • The y-intercept is (0, -2).

Example 1

  • Find the x and y intercepts for y = 2x + 6
  • To find the y intercept, y = 2(0) + 6, y=6.
  • The y intercept coordinates are (0,6)
  • To find the x intercept, 0 = 2x + 6, x = -3
  • The x intercept coordinates are (-3,0)

Example 2

  • Find the x and y intercepts for y = 3x + 12
  • To find the y intercept, y = 3(0) + 12, y = 12
  • The y intercept coordinates are (0,12)
  • To find the x intercept, 0 = 3x + 12, x = -4
  • The x intercept coordinates are (-4,0)

Practice Time Equations

    1. y = (1/2)x + 4
    1. y = -2x + 8
    1. y = -3x - 4
    1. y = 8x - 2
    1. 2x + 3y = 6
    1. 5x + 2y = 10
    1. -3x + 5y = 9
    1. -2x - 3y = 10

Further Practice Questions and Answers

    1. y = (1/2)x + 4
  • The y intercept coordinates are (0,4) and the x intercept coordinates are (-8,0)
    1. y = -2x + 8
  • The y intercept coordinates are (0,8) and the x intercept coordinates are (4,0)
    1. y = -3x - 4
  • The y intercept coordinates are (0,-4) and the x intercept coordinates are (-4/3,0)
    1. y = 8x - 2
  • The y intercept coordinates are (0,-2) and the x intercept coordinates are (1/4,0)
    1. 2x + 3y = 6
  • The y intercept coordinates are (0,2) and the x intercept coordinates are (3,0)
    1. 5x + 2y = 10
  • The y intercept coordinates are (0,5) and the x intercept coordinates are (2,0)
    1. -3x + 5y = 9
  • The y intercept coordinates are (0,9/5) and the x intercept coordinates are (-3,0)
    1. -2x - 3y = 10
  • The y intercept coordinates are (0,-10/3) and the x intercept coordinates are (-5,0)

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