Question

please help.....I need to solve for x and y

Answer 1

27.98(x/100) + 28.98(0.468) + 29.97(y/100) = 2
I have done it, but I don't know if it is correct.
I got : x = 4.75 and y = - 2.3

Answer 2

@jim_thompson5910 ...can you check this please

Answer 3

I had to do quite a bit of rounding

Answer 4

\[27.98\frac{x}{100}+28.98(0.468)+29.97\frac{y}{100}=2\]Multiply through by 100
\[27.98x + 28.98(46.8) + 29.97y=200\]\[27.98x+29.97y=-1156.26\]Plug in your values
\[27.98(4.75)+29.97(-2.3) = 132.905 - 68.931\] no cigar...

Answer 5

What were the original equations you had to solve? You've only got 1 equation in 2 unknowns there...

Answer 6

That is the entire problem

Answer 7

This is how I did it ...
http://answers.yahoo.com/question/index;_ylt=AhbRn18tPXL8JzIQK3FKflPsy6IX;_ylv=3?qid=20130606164535AAjXXiq

Answer 8

Well, first solve for one of your variables, let's start with y. Solving for y we get y=-0.9336x-38.5807. Plug that back into your equation and you get 0.2798 x+0.2997 (-0.9336x-38.5807)+13.5626 = 2
Just solve for x then you'll be able to solve for y.

Answer 9

Unfortunately you made an arithmetic error on the very first line :-(

Answer 10

(@texaschic101 that is)

Answer 11

28.98*0.468 = 13.5626

Answer 12

I got x=447.37 and y=-456.245

Answer 13

Oh darn.....messed up on the first line...thats bad....makes the entire problem wrong

Answer 14

0.2798x + 0.2997(-0.9336x - 38.5807) + 13.5626 = 2
@whpalmer4 ....can the numbers be rounded to make them shorter ?

Answer 15

because when I distribute the numbers are really long

Answer 16

you can round them at a cost of accuracy in the final result...

Answer 17

so your saying that it is best not to round ?

Answer 18

yes, if you want an answer that makes the problem come out as close as possible...

for example, Brenar's numbers (even though they have many digits) give 2.00014 as the answer...

Answer 19

if you just don't like all the writing, why not substitute letters for each different number?
ax + b(-cx-d)+e=2
a=0.2798, b=0.2997, etc.
then when you've solved for x and y, plug in the numbers

Answer 20

I wouldn't actually do the multiplication until the last possible opportunity...

Answer 21

0.2798x - .27979992x - 11.5405479 + 13.5626 = 2
my calculator is throwing in letters when I try to subtract :/

Answer 22

ax + b (-cx + d) + e = 2
ax -bcx + db + e = 2
ok...I am so lost

Answer 23

there is no unique solution here, you realize?

Answer 24

I really don't know why I am doing this problem...it is not even my problem...it just caught my attention

Answer 25

Your original equation is \[27.98(x/100) + 28.98(0.468) + 29.97(y/100) = 2\]Multiply through by 100:
\[27.98x + 28.98(46.8) + 29.97y = 200\]Solve for \(y\)\[29.97y = 200-28.98(46.8)-27.98x\]\[y=\frac{1}{29.97}(200-28.98(46.8)-27.98x)\]

Now pick a value of \(x\) and plug it into the formula. Out pops the matching value of \(y\). For any value of \(x\), there's a corresponding value of \(y\). The solution is a straight line...

Answer 26

If you like, you can write it as \(y = -38.5807-0.9336x\)

Answer 27

I like that better

Answer 28

It's just a real-life equation for a line, instead of a sanitized equation like you get in the textbook :-)

Answer 29

Because we have fewer equations than we have unknowns, we don't get a unique solution.

Answer 30

thank you so much @whpalmer4 and @Brenar ......you are great. Did you ever think about being teachers.

Answer 31

Hard to get a teaching job where you get to teach only the interested students :-)

Answer 32

I deleted my answer on yahoo....didn't want to give that person a wrong answer...I should refer him to you...lol

Answer 33

thanks again :) I will close this question now

Answer 34

you're welcome!