Optional: Here is a prove that product of the slopes of two perpendicular lines is -1 by using the knowledge you have learned. https://www.youtube.com/watch?v=DAeXPJ3Jd2Y Today I introduced the concepts of intercept and slope. Please note that the slope-intercept form of linear equation with two variables provides the information of slope and y-interept directly. Although you also can get the slope and intercept based on their definitions, it is much convenient to obtain them by using the slope-intercept form. Here are the concepts and some related examples: Rectangular coordinate system
The horizontal axis is called the x-axis. The vertical axis is called the y-axis. The interception of x-axis and y-axis is a point called origin. The axes divide the plane into regions, called quadrants (I, II, III , and IV). In the ordered pair (1,-1), the 1 is called x-coordinate, and -1 is called y-coordinate. Each ordered pair of numbers corresponds to one point in the plane. The solution of an equation in two variables can be represented by an ordered pair. The graph of y=a (a is a constant) is a horizontal line. The graph of x=a (a is a constant) is a vertical line. Linear equation with two variables The standard form of linear equation: Ax+By=C (A, B, C are constant, A and B could not be zero at the same time). Graph the linear equation with two variables Find two ordered pair solutions, and connect these two points (the third point in following examples is not necessary). |
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