2e Worksheet 2 (simultaneous Eqns - Eliminatn Method)

CORALSECONDARYSCHOOL ELEMENTARYMATHEMATICS WORKSHEET2 : SIMULTANEOUSEQUATIONS (ELTMTNATTON METHOD) (

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Se c2 l 1.

Date: Elimination Method

Method:

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Determinewhich variableyou want to eliminate. Is it the "x" or is it the "y" that you want to eliminate(get rid offl).

2.

Ensure that the coefficient of the variable that you have decided to eliminate is the same. To do this you may be required to multiply a certain factor into one of the equationsso that the coefficientsbecomethe same. There are some caseswhere you may be requiredto multiply different factorsto eachequationso that the coefficientof the variableyou have decidedto eliminateare the same.

3.

Look at the coefficient of the variablesthat you want to eliminate. If the signsare the same(e.g.if both coefficientsare"2" or both coefficientsare " -2 ") then we subtract one equationfrom another.If the signsare different (e.g."2" and" -2") then we add both equations.

4.

We will then solve for the unknown and use this value to find the other unknown by substitutingthe value into any of the two original equations.

5.

To check if your solution is correct, substitutethe values of x and y into any of the original equationand you shouldobtainthe right hand side.

2.

Examples

2.1

Solvethe pair of simultaneous equations: x*Y =) x*Y =4 Eliminate "x"

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Eliminate'6y"

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2E Worksheet2: SimultaneousEquations(Elimination Method)

2.2

Solvethe pair of simultaneousequations: 4x+5Y =12 2x +3r =12

2.3

Solvethe pair of simultaneous equations: 7x-2Y =$ 5x -3Y : -2

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2E Worksheet2: SimultaneousEouations(El.iminationMethod)

2.4

Solvethepairof simultaneous equations: 3 x-2 Y =J 2 x+7 Y =)J

2.5

Solvethe pair of simultaneousequations: I

5 x+:v=1 3 a/ J

7 x-y=5

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2E Worksheet2: SimultaneousEquations(Elimination Method)

2.6

equations: Solvethe pair of simultaneous x.y

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2.7

There are two queuesat a bus stop at a certain time. The number of people in the queuesarex andy respectivelyandx> y. (i) If the difference in the number of people in these two queuesis 10, form an equationconnectingx andy. (ii) If the first queue is twice as long as the second queue, form an equation connectingx andy. (iii) Solve the simultaneousequationsobtained in (i) and (ii). Hence find the numberof peoplein eachqueue.

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E x 5 .4 Q l g ,2 a , g

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Ex 5.4 Q1b, e,2b, e, h, 3; OptionalQuestion:Q5

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