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Example 1

Use graphical method to solve the following pairs of simultaneous equations

  1. y = 3x – 5      and     y = -2x -7
  2. 4y – 2x = 4     and    2y + x = 10

Solution:

When plotting the graph of a linear curve, it is sufficient to get 2 points or 3 points.

The coordinates of points of intersection of the curves give the solution to the equations.

y = -2x -7

X-2-10
Y-3-5-7

y = 3x – 5

X-102
Y-8-51

Diagram of Simultaneous Equation Graph

simultaneous equations

intersection x = -0.4,  y = -6.2       i.e.    (-0.4, -6.2)

ii. 4y – 2x = 4

y = \( \frac{x}{2} \; + \; \scriptsize 1 \)

X345
Y2.533.5

2y + 2 = 10

y = \( \frac{-x}{2} \; + \; \scriptsize 5 \)

X345
Y3.532.5

Diagram of Simultaneous Equation Graph 

Screen Shot 2021 01 28 at 7.25.51 AM

At the intersection the coordinates is given as x = 4,  y = 3

i.e.      (4,  3).

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