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How To Test For Symmetry

Graphs and Symmetry

I.  Homework

2.  Symmetry (Geometry)

We say that a graph is symmetric with respect to the y axis if for every indicate (a,b) on the graph, there is likewise a point (-a,b) on the graph.  Visually we have that the y axis acts as a mirror for the graph.  We will demonstrate several functions to examination for symmetry graphically using the graphing calculator.

We say that a graph is symmetric with respect to the ten axis if for every betoken (a,b) on the graph, there is also a indicate (a,-b) on the graph.  Visually we have that the x axis acts as a mirror for the graph.  Nosotros volition demonstrate several functions to test for symmetry graphically using the graphing estimator.

Nosotros say that a graph is symmetric with respect to the origin if for every point (a,b) on the graph, at that place is too a point (-a,-b) on the graph.  Visually we have that given a point P on the graph if we draw a line segment PQ through P and the origin such that the origin is the midpoint of PQ, and then Q is also on the graph.  We volition utilise the graphing calculator to examination for all iii symmetries.

4.  Symmetry (Algebra)

To test algebraically if a graph is symmetric with respect the x axis, we replace all the y'south with -y and meet if we get an equivalent expression.

Examples:

A)  For x - 2y = v nosotros replace with x - 2(-y) = 5.  Simplifying we get

ten + 2y = v which is not equivalent to the original expression.

B)  For x3 - y2 = 2 nosotros replace with   tenthree - (-y)2 = two which is equivalent to the original expression, so that x3 - yii = 2 is symmetric with respect to the 10 centrality.

To test algebraically if a graph is symmetric with respect to the y axis, we supervene upon all the x's with -10 and see if we become an equivalent expression.

Example:

A)  For y = 10two we supercede with y = (-ten)two =  x2 so that y = xii is symmetric with respect to the y axis.

B)  For y = ten3 we replace with  y = (-x)3 = - x3 so that y = 103 is non symmetric with respect to the y axis.

To test algebraically if a graph is symmetric with respect to the origin we replace both x and y with -ten and -y and meet if the result is equivalent to the original expression.

Examples:

A)  For y = xthree, we replace with (-y) = (-x)3 so that -y = -xthree or y = xiii.  Hence  y = 103 is symmetric with respect to the origin.

B)  For y = x2 we replace with -y =  (-10)two and then that -y = x2 or y = -x2.  Hence y = tenii is non symmetric with respect to the origin.

We volition do other examples in class as a grouping.

5.  Intercepts

We define the x intercepts as the points on the graph where the graph crosses the x axis.  If a point is on the 10 axis, and then the y coordinate of the bespeak is 0.  Hence to find the ten intercepts, we set y = 0 and solve.

Example:  Notice the 10 intercepts of

y = 10ii + x - two

We prepare y = 0 so that

0 =  102 + x - 2 = (x + ii)(x - ane)

Hence that x intercepts are at (-2,0) and (1,0)

We define the y intercepts of a graph to be the points where the graph crosses the y axis.  At these points the x coordinate is 0 hence to fine the y intercepts nosotros gear up x = 0 and detect y.

Example:   Detect the y intercepts of  y = x2 + ten - 2

Solution:  We ready x = 0 to get:  y = 0 + 0 - 2 = -2.

Hence the y intercept is at (0,-2).

How To Test For Symmetry,

Source: http://www.ltcconline.net/greenl/courses/103a/premid1/symm.htm

Posted by: creedeneas1998.blogspot.com

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