Easy points Maths question please help?

👨🏻‍🏫 學術台數學

[匿名]

2009-01-17 10:57 am

how how i go about finding x and y for this equation

2x +3y =6
3x-4y=8 thanks

更新1:

and for this one 3x-3y=6 3x-y=6 the answer is x=2 and y=0 but how come we only need to the elimination onceon the y's only? is it because it wasnt a fraction?

回答 (8)

Engr. Ronald

2009-01-17 11:51 am

✔ 最佳答案

[2x +3y =6]4
[3x-4y=8]3

8x+12y=24
9x-12y=24
--------------------
17x =48
x=48/17

2[48/17]+3y=6
96/17+3y=6
3y=6-96/17
3y=6/17
y=6/17/3 =6/51 answer

3x-3y=6
3x-y=6
----------------
-4y=12
y=-3

3x-3(-3)=6
3x+9=6
3x=6-9
3x=-3
x=-1

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[匿名]

2009-01-17 7:06 pm

solve simutaneously

2x +3y =6
3x-4y=8

2x=6-3y

x=3-3/2y

sub x back in

9-9/2y-4y=8

9/2y-4y=-1

1/2y=-1
y=-2

sub y back in

2x-6=6

2x=0

x=0

therefore y=-2 and x=0

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[匿名]

2009-01-17 7:12 pm

2x + 3y = 6 multiply by 3
3x - 4y = 8 multiply by 2
6x + 9y = 18
6x - 8y = 16
Now subtract them.
17y = 2
y = 2/17
Substitute y into an original equation
2x + 3y = 6
2x + 3 x 2/17 = 6
2x + 6/17 = 6
2x = 6 - 6/17
2x = 96/17
x = 96/17 / 2
x = 48/17

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[匿名]

2009-01-17 7:11 pm

2x + 3y =6 Eq (1)
3x – 4y =8 Eq. (2)

Eliminate y
8x + 12y = 24 Eq (1) x 4
9x – 12y = 24 Eq. (2) x 3
---------add-------------------------
17x = 48
x = 48/17

Eliminate x
6x + 9y = 18 Eq (1) x 3
6x – 8y = 16 Eq. (2) x 2
-------subtract----------------
17y = 2
y = 2/17

(x, y) = (48/17, 2/17)

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[匿名]

2009-01-17 7:10 pm

sub

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An ESL Learner

2009-01-17 7:10 pm

2x + 3y = 6 (solve by using elimination)
3x - 4y = 8

2x + 3y = 6
3(2x + 3y) = 3(6)
6x + 9y = 18

3x - 4y = 8
2(3x - 4y) = 2(8)
6x - 8y = 16

...6x + 9y = 18
–) 6x - 8y = 16
-----------------------------
17y = 2

17y = 2
y = 2/17

2x + 3y = 6
2x + 3(2/17) = 6
2x + 6/17 = 6
2x = 102/17 - 6/17
x = (96/17)/2
x = (96/17)(1/2)
x = 48/17

â´ x = 48/17 , y = 2/17

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[匿名]

2009-01-17 7:10 pm

Use substitution or elimination

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[匿名]

2009-01-17 7:07 pm

x=48/17 and y=2/17

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