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Katchi_2003
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#1
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#1
Hey any of you good people know this answer it is for my homework:

2x=10-3y
3x+ 19=4y

Method and answer; i will be grateful
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Bhaal85
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#2
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(Original post by Katchi_2003)
Hey any of you good people know this answer it is for my homework:

2x=10-3y
3x+ 19=4y

Method and answer; i will be grateful
solve simultaneously.

2x=10-3y x3
3x=4y-19 x2

6x=20-9y
6x=8y-38

0=58-17y
y=58/17
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Sir I. Newton
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(Original post by Katchi_2003)
Hey any of you good people know this answer it is for my homework:

2x=10-3y
3x+ 19=4y

Method and answer; i will be grateful
6x = 30 - 9y
6x = 8y - 38

17y - 68 = 0 , y = 4
2x = 10 - 3(4) = -2
x = -1
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Katchi_2003
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thank you, can you show me the checking method
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Nylex
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#5
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3y = 10-2x => y = (10-2x)/3

Substitute this into other equation:

4((10-2x)/3) = 3x + 19

(40-8x)/3 = 3x + 19

40-8x = 9x + 57
40-57 = 17x => x = -1

Then substitute into either of your original equations to get y.
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Lucy
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#6
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#6
bhaal 10 x 3 = 30
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Bhaal85
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#7
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(Original post by Lucy)
bhaal 10 x 3 = 30
Whoops.........that was meant to test you other peeps. lol.
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Katchi_2003
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(Original post by Bhaal85)
Whoops.........that was meant to test you other peeps. lol.

Man i done it but the check doesnt work, can someone show me how its done with full method and working, i be grateful.
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Lucy
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Ok this is what I did:

First I rearranged the formulae:

2x = 10-3y (1)
3x = 4y-19 (2)

Then I did the formula (1) times 3 to make:
6x = 30 - 9y (3)

and I multiplied the formula (2) by 2 to make:
6x = 8y - 38 (4)

Then I did formula (4) minus formula (3) to make:
0 = 17y-68
therefore 17y=68
y = 4

I substituted y into formula (1) to get:
2x = -2
therefore x = -1

Substituted both values of x and y into (2) to check my values were correct.

Hope this is a bit clearer
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Katchi_2003
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#10
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(Original post by Lucy)
Ok this is what I did:

First I rearranged the formulae:

2x = 10-3y (1)
3x = 4y-19 (2)

Then I did the formula (1) times 3 to make:
6x = 30 - 9y (3)

and I multiplied the formula (2) by 2 to make:
6x = 8y - 38 (4)

Then I did formula (4) minus formula (3) to make:
0 = 17y-68
therefore 17y=68
y = 4

I substituted y into formula (1) to get:
2x = -2
therefore x = -1

Substituted both values of x and y into (2) to check my values were correct.

Hope this is a bit clearer

I Solved it in my way that method is right i [email protected]

2x+3y=10 > 1
3x-4y=19 > 2

>1 *4

8x+12y = 40 >3

>2* 3

9x-12y=57 > 4

8x+12y = 40 >3
9x-12y =57 > 4

4-3

1x=17
x=17

subst in 1:

34 + 3y = 10
3y = -24
y= -8

x=17
y= -8

check in 2:

51 - 32 = 19

3x-4y=19

thanks for all yr help
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Lucy
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#11
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The formula you posted originally i.e. 3x +19 = 4y does not equal what you just posted now i.e. 3x - 4y = 19... it equals 3x - 4y = -19
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CHAD
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#12
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(Original post by Bhaal85)
solve simultaneously.

2x=10-3y x3
3x=4y-19 x2

6x=20-9y
6x=8y-38

0=58-17y
y=58/17
AFTER THIS U ADD 17y to both sides so u have

17y = 58

then u divide by 17 so u r left with

y= 58 divided by 17
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Bhaal85
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#13
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#13
(Original post by CHAD)
AFTER THIS U ADD 17y to both sides so u have

17y = 58

then u divide by 17 so u r left with

y= 58 divided by 17
yeah, I know hence y=58/17. But its wrong, if you really look at it.
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Lucy
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#14
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(Original post by CHAD)
AFTER THIS U ADD 17y to both sides so u have

17y = 58

then u divide by 17 so u r left with

y= 58 divided by 17
We have already discovered that this is wrong as 2x=10-3y (x3) does not equal 6x = 20-9y therefore all the steps after that are incorrect (even though method is correct)
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Bhaal85
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#15
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(Original post by Lucy)
We have already discovered that this is wrong as 2x=10-3y (x3) does not equal 6x = 20-9y therefore all the steps after that are incorrect (even though method is correct)
Like I said before, it was a test
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Lucy
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#16
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#16
Lol but now you've gone and confused everyone!
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Saf!
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#17
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#17
as u'r all talkin about maths..... is anyone doin the gcse maths c/wk where u have 2 find the difference of the products in a number grid??

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ShOcKzZ
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#18
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(Original post by Saf!)
as u'r all talkin about maths..... is anyone doin the gcse maths c/wk where u have 2 find the difference of the products in a number grid??

nup.
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Saf!
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#19
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(Original post by ShOcKzZ)
nup.
i know theres loads of u who have dun it!!! :mad:
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Nylex
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#20
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Why did this question have "tricky" in the title??
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