solve using elimination method

sisapeebles

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May 20, 2011
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please help me solve using the elimination method:
0.3x - 0.2y=4
0.5x + 0.5y=85/19

thank you!!!
 

Subhotosh Khan

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Jun 18, 2007
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18,135
sisapeebles said:
please help me solve using the elimination method:
0.3x - 0.2y=4
0.5x + 0.5y=85/19

thank you!!!
Suppose the equations are:

ax + by = c and......................(1)
dx + ey = f ...........................(2)..........................(where a,b,c,d,e &f are non-zero constants)

Then we multiply top equation by 'd' and bottom equation by 'a'. We get

adx + bdy = cd..............................(3)
adx + aey = af..............................(4)

Now subtract (4) from (3) - We get

y (bd-ae) = cd - af (where bd-ae is not equal to zero)

y = (cd - af)/(bd -ae)

You found the value of 'y'.

Use this value in (1) or (2) to find 'x'.

Finally check your answer, by putting these values of 'x' and 'y' in (1) and (2).

If you need more refresher, go to:

http://www.purplemath.com/modules/systlin6.htm
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,465
sisapeebles said:
0.3x - 0.2y=4
0.5x + 0.5y=85/19
Start by multiplying by 10 to get rid of decimals:
3x - 2y = 40
5x + 5y = 850/19

Now follow Subhotosh's hints...
 
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