Help w/ 2 simple algebra questions please!

Toddy · #1 10-12-2006, 12:23 PM

If anyone could answer these i would be forever grateful.

Solve for x.
x - 2y + 1 = 0

Simplify.
9/y² - 1 / 1+3/y

Thank You

Im doing 40 problems and these 2 i can't figure.

Utah · #2 10-12-2006, 12:29 PM

x = 2y-1
9y+27-y^3

Toddy · #3 10-12-2006, 12:35 PM

[ QUOTE ]
x = 2y-1
9y+27-y^3

[/ QUOTE ]

TY but the 2nd one the mulitple choice is

A.3
B. y
C 1-y
D 3-y/y

Jasper109 · #4 10-12-2006, 12:50 PM

[ QUOTE ]
[ QUOTE ]
x = 2y-1
9y+27-y^3

[/ QUOTE ]

TY but the 2nd one the mulitple choice is

A.3
B. y
C 1-y
D 3-y/y

[/ QUOTE ]

D

(factor the numerator as a difference of squares, cancel, and then find a common denominator for the binomial left over)

If you are stuck and the question is multiple choice, just substitute any number for the variable and see which of the choices gives you the same value as the original question.

Utah · #5 10-12-2006, 01:37 PM

D 3-y/y

Why wouldnt D simply be 3-1 = 2?

Can you show you steps. I am missing something obvious here.

Jasper109 · #6 10-12-2006, 01:39 PM

[ QUOTE ]
D 3-y/y

Why wouldnt D simply be 3-1 = 2?

Can you show you steps. I am missing something obvious here.

[/ QUOTE ]

(3-y)/y not 3-(y/y)

(3-y)y = 3/y - y/y
which is 3/y - 1

Utah · #7 10-12-2006, 01:50 PM

(3-y)/y

Lets try 1

(3-y)/y = (3-1)/1 = 2

9/y² - 1 / 1+3/y = 9/1 - 1 /(1+3/1) = 9-.25 = 8.75

What am I missing here?

Jasper109 · #8 10-12-2006, 01:56 PM

[ QUOTE ]
9/y² - 1 / 1+3/y = 9/1 - 1 /(1+3/1) = 9-.25 = 8.75

[/ QUOTE ]

((9/1) - 1)/(1 + (3/1))

(9 - 1)/(1 + 3)

8/4

2

Order of operations!!!

Utah · #9 10-12-2006, 02:07 PM

[ QUOTE ]
[ QUOTE ]
9/y² - 1 / 1+3/y = 9/1 - 1 /(1+3/1) = 9-.25 = 8.75

[/ QUOTE ]

((9/1) - 1)/(1 + (3/1))

(9 - 1)/(1 + 3)

8/4

2

Order of operations!!!

[/ QUOTE ]Thanks. Well son of a #$#@$ @#!#@. The original equation is not stated correctly.

9/y² - 1 / 1+3/y <> (9/y^2 -1) / (1/(1+3/y)
ie. I read it as (9/y^2) - (1/(1+3/y)), which is much harder. I added the () around 1+3/y because 1/1 didnt make sense.

Do they not make you use parenthesis is school anymore [img]/images/graemlins/smile.gif[/img]

I thought I was stupid for a sec, but I have a math major who works for me and he came up with the same answer I did (not my answer above, which was sloppy and incorrect).

Jasper109 · #10 10-12-2006, 02:22 PM

I just think it's really difficult to write algebra related things with a standard keyboard.

I could just see right away what the statement probably was saying based on 20+ years of teaching factoring and rational expressions.