Good at Math? Heres ten points!!?

👨🏻‍🏫 學術台數學

[匿名]

2009-03-30 3:05 am

Give correct answer as well as best detailed explanation on how to solve it to get chosen best answer!

Solve using elimination by addition (algebra)

5x = 3y + 3
3x + 5y = 4

更新1:

thw responder named Reset is correct, its solving systems of linear equations by using Elimination by addition. No graphs nor anything else is neccessary to compute the problem

回答 (11)

[匿名]

2009-03-30 3:24 am

✔ 最佳答案

5x - 3y = 3 (rewrite the 1st equation)
3x + 5y = 4

25x - 15y = 15 (multiply 1st equation by 5)
9x + 15y = 12 (multiply 2nd equation by 3)

Adding 1st & 2nd equations to eliminate y, you get:

25x - 15y + 9x + 15y = 15 + 12
34x = 27
x = 27/34

Now put x= 27/34 to equation 1
5(27/34) = 3y + 3
y = (5(27/34) - 3)/3
y = (135/34 - 3)/3
y = 11/34

👍 0 👎 0

nozar nazari

2009-03-30 10:20 am

x=3(y+1)/5 , x=(4-5y)/3, (9y+9)=20-25y,34y=11,y=11/34

👍 0 👎 0

[匿名]

2009-03-30 10:18 am

5x = 3y + 3 and 3x + 5y = 4
--->5x-3y=3 and 3x + 5y = 4
it is a system
(3) 5x-3y=3 ----> 15x-9y=9
(-5) 3x + 5y = 4 ----> -15x-25y=-20
15x-15x-9y-25y=9-20
-34y=-11
y=11/34

5x=3y+3
5x=(3*(11/34))+3
5x=(33/34)+3
5x=(33+102)/34
5x=135/34
x=27/34

x=27/34 and y=11/34

👍 0 👎 0

[匿名]

2009-03-30 10:18 am

5x-3y=3
3x+5y=4

15x-9y=9ãã (1)
15x+25y=20ã(2)

(2)-(1)
34y=11
y=11/34
x=27/34

👍 0 👎 0

[匿名]

2009-03-30 10:16 am

multiply (1) by 3

multiply (2) by -5

=

15x = 9y + 9
-15x -25y = -20

add (1) and (2)

-25y =9y -11

-34y = -11

y = 11/34

sub back into any of the original ( i use (1))

5x = 3(11/34) + 3

x = 27/34

👍 0 👎 0

[匿名]

2009-03-30 10:18 am

5x-3y=3 (x3)
3x+5y=4 (x5)

it becomes

15x-9y=9
15x+25y=20
------------------
-16y=29
----- ----
-16 -16

y= 29/-16

i dunno if im totally correct. :P

參考: myself

👍 0 👎 1

[匿名]

2009-03-30 10:17 am

I know how to do it, but... i'm to lazy

👍 0 👎 1

[匿名]

2009-03-30 10:13 am

huh.. i dont think i understand..

👍 0 👎 1

[匿名]

2009-03-30 10:12 am

is that all of the question or is their a graph??

👍 0 👎 1

[匿名]

2009-03-30 10:08 am

First take one of the equations and write it isolating one of the variables. It doesn't matter which equation or which variable it will always be the same answer.

I will use the first equation.

x = (3/5)y + 3/5

Now use the right side of this equation as x in the second equation.

3((3/5)y + 3(3/5)) + 5y = 4

expand that

(9/5)y + 9/5 + 5y = 4

At this point i would multiply everything by 5 to get rid of the fractions.

9y + 9 +25y = 20

34y = 11

y = 11/34 now go back to the first equation and substitute this answer for y.

5x = 3*11/34 +3

5x = 113/34

x = 113 /170

Next check your work by inputting these answers into the second equation.

i think i did something wrong but thats how you do it anyways

👍 0 👎 1

收錄日期: 2021-05-01 12:13:45
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090329190508AA4yfbG

檢視 Wayback Machine 備份