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- The graph of an equation consists of all the points which satisfy or
solve the equation.
- Solve the equation to find the points, then plot the points.
- These points are called coordinates.
- Each point (coordinate) consists of one value for y and one value for x,
and is written as the ordered pair
(x, y).
- The values of (x, y) solve the equation
y = x + c,
- where c represents a constant value
- The coordinates are ordered pairs of real numbers.
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- x and y are most commonly used as variables in an equation
- Variables are placeholders for values
- Variable y is dependent on the variable x
- The independent variable, x, is plotted along the horizontal axis (x
axis)
- The dependent variable, y, is plotted along the vertical axis (y axis)
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4
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- Consider the linear equation y
= x + 2
- The y value is dependent on the value of x
- Find ordered pairs by assigning any value to x
- Let x = 0 and solve for y to find (0, y)
- y = 0 + 2 or y = 2 The ordered pair is (0, 2)
- Let x = 1 and solve again for y to find (1, y)
- y = 1 + 2 or y = 3 The ordered pair is (1, 3)
- Let x = -2 and solve again for y to find (-2, y)
- y = -2 + 2 or y = 0 The ordered pair is (-2, 0)
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5
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- Solutions for y = x + 2 put in a table form
- x y
- 0 2
- 1 3
- -2 0
- -1 1
- Graph of y = x + 2
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6
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- y = 2x + 3 is the graph of a straight line
- y = 2x2 + 3 is the graph of a curved line called a parabola
- y2 = 2x2 + 3 and y = x3 + 3 are also
curved line graphs
- Graphs are drawn by solving the equations and plotting the ordered
pairs.
- Draw the simplest graph you can to connect all the points.
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