S2A Chapter 4 Simultaneous Equations

2009 Chung Tai Educational Press. All rights reserved. © Simultaneous Linear Equations in Two Unknowns  (  1)  2(2)  3 (  1)  3(2)   7  x   1 and y  2 is the solution of the simultaneous equations. are simultaneous linear equations in two unknowns

2009 Chung Tai Educational Press. All rights reserved. © Graphical Method The coordinates of the point of intersection is the solution of the simultaneous linear equations in two unknowns. In the graph, two straight lines intersect at (  1, 2).  The solution of the simultaneous equations is x   1, y  2. x  3y   7 x  2y  3

2009 Chung Tai Educational Press. All rights reserved. © From (1), x  3  2y (3) Substitute (3) into (2), 3 – 2y – 3y   7  5y   10 y  2 Substitute y  2 into (3), x  3  2(2)   1  The solution of the simultaneous equations is x   1, y  (1) (2) Method of Substitution

2009 Chung Tai Educational Press. All rights reserved. © Method of Elimination (1) – (2),5y  10 y  2y  2 Substitute y  2 into (1), x  2(2)  3 x   1  The solution of the simultaneous equations is x   1, y  (1) (2)

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