Monday, May 27, 2013

Solve Graphing Test

Introduction to solve graphing test:

Solve graphing test is one of interesting topics in mathematics. Without doing any algebraic manipulations, we can solve two simultaneous equations in x and y by drawing the graphs corresponding to the equations together. An equation in x and y is of the form a x + b y + c = 0. The equation represents a straight line, so, the problem of solving two simultaneous equations in x and y reduces to the problem of finding the common point between the two corresponding lines.
Steps to solve the graph:


The following steps are necessary to solve the graphing test:


Step 1:

 Two different values are substitute for x in the equation y = mx + b, we get two values for y. Thus we get two points (x1, y1) and (x2, y2) on the line.
Step 2:

   Draw the x-axis and y-axis on the graph and choose a suitable scale on the co- ordinate axes. Both the axes is chosen based on the scale values of the co-ordinates obtained in step 1. If the co-ordinate values are large in given data then 1 cm along the axes may be taken to represents large number of units.
Step 3:

Plot the two points (x1, y1) and (x2, y2) in Cartesian plane of the paper.

Step 4:

 Two points are joined by a line segment and extend it in both directions of the segment. Then it is the required graph.


Examples to solve graphing test:


Examples to solve graphing test are as follows:

Example 1:

   Draw the graph y = 3x −1.

Solution:

   Substituting x = −1, 0, 1 in the equation of the line, we get y = −4, −1, 2 correspondingly. In a graph, plot the

   Points (−1, −4), (0, −1) and (1, 2).



  X    -1    0    1

  Y    -4   -1    1

  Join the points by a line segment and extend it in both directions. Thus we get the required linear graph



    Example 2:

    Draw the graph of the line  2x  + 3y  = 12.

Solution:

  The given equation is rewritten as 3y = −2x + 12 or y = (−3 / 2)x  + 4.

  Substituting  x = −3 then y = 6

 x = 0, then y = 4
x = 3 then y = 2.

  Plot x and y values in the graph sheet. [(−3, 6), (0, 4) and (3, 2)]

  X    -1      0        1

  Y   5.5     4       2.5

  Join the points by a line segment and extend it in both the directions. Then it is the required linear graph.

Practice problems to solve graphing test:


Some practice problems to solve graphing test

1. Draw the graph of the following : y  = −2x

 Answer:     x    -1   0   1

  y     2   0  -2

 2. Draw the graph of the following equations:  y + 2x −5 = 0.
Answer:    x    -1   0   1
y     7   5   3

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