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Home Q & A Board Science-Related Homework Help Mathematics
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Julieoct Julieoct
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11 years ago
3x - 10y = -25
4x + 40y = 20

Could someone show me how to solve this system using elimination?
Show your work so I can do the other 20 problems I have to do...

Greatly appreciated + best answer for you! :]
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MickymouseMickymouse
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#1
11 years ago
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#2
11 years ago
for this one you multiply the top by 4 and add to the 2nd...solve for x , then for y

in general multiply the 1st by -4/3 and add to the 2nd , solve the new 2nd for y , back into the 1st and solve for x
wrote...
#3
11 years ago
3x - 10y = -25
4x + 40y = 20

Multiply line 1 by 4

12x - 40y = -100
4x + 40y = 20

Add the two above, giving

16x = -80

x = -80/16

x = -5

Then 10y = 3x+25, y = (3(-5)+25)/10 = 1

Thus x = -5, y = 1
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