Math Help Forum

Math Help Forum Feed Site Feed

Go Back   Math Help Forum > Pre-University Math Help > Pre-Algebra and Algebra
Reply
 
Thread Tools Display Modes
  #1  
Old May 13th, 2008, 02:44 AM
Newbie
 
Join Date: May 2008
Posts: 7
Country:
Thanks: 0
Thanked 0 Times in 0 Posts
bubbles73 is on a distinguished road
Default Solving coefficients

Equations
1. 10 = 121a+11b+c
2. x = -b/2a
3. 35 = -b^2/4a + c
4. b = 4.8233-22a

There are 4 unknowns and 4 equations. After numerous attempts of trying to find a i could really use some help. The actual value of a is -0.233 or part there of. Here is my best attempt, i cant see where i went wrong.

equation 3. c = 35 + b^2/4a

10= 121a+11b+35+b^2/4a
10=121a+53.0563-242a+35+ (9.6466-212.2252+484a^2 all over 4a)
40a = 212.2252a-484a^2+140a+9.6466-212.2252a+484a^2
40a=140a+9.6466
100a= - 9.6466
a = -0.096466
Reply With Quote
Advertisement
 
  #2  
Old May 13th, 2008, 07:11 AM
masters's Avatar
He's dead, Jim

 
Join Date: Jan 2008
Location: Big Stone Gap, Virginia
Posts: 2,045
Country:
Thanks: 511
Thanked 1,769 Times in 1,211 Posts
masters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant futuremasters has a brilliant future
Default

Quote:
Originally Posted by bubbles73 View Post
Equations
1. 10 = 121a+11b+c
2. x = -b/2a
3. 35 = -b^2/4a + c
4. b = 4.8233-22a

There are 4 unknowns and 4 equations. After numerous attempts of trying to find a i could really use some help. The actual value of a is -0.233 or part there of. Here is my best attempt, i cant see where i went wrong.

equation 3. c = 35 + b^2/4a

10= 121a+11b+35+b^2/4a
10=121a+53.0563-242a+35+ (9.6466-212.2252+484a^2 all over 4a) You multiplied 4.8233 by 2 instead of squaring it. Should be 23.26422289.
40a = 212.2252a-484a^2+140a+9.6466-212.2252a+484a^2
40a=140a+9.6466
100a= - 9.6466
a = -0.096466
I tried finishing it out after correcting the mistake, but ended up with a = 1.488707008. There's a lot of numbers there. Could've gone wrong somewhere.
__________________
He who knows not and knows not that he knows not is a fool, shun him. He who knows not and knows that he knows not is a child, teach him. He who knows and knows not that he knows is asleep, wake him. And he who knows and knows that he knows is wise, follow him.
-- Persian Proverb



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #3  
Old May 13th, 2008, 07:18 AM
earboth's Avatar
Super Member

 
Join Date: Jan 2006
Location: Germany
Posts: 4,186
Country:
Thanks: 177
Thanked 1,809 Times in 1,660 Posts
earboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant futureearboth has a brilliant future
Default

Quote:
Originally Posted by bubbles73 View Post
Equations
1. 10 = 121a+11b+c
2. x = -b/2a
3. 35 = -b^2/4a + c
4. b = 4.8233-22a

There are 4 unknowns and 4 equations. After numerous attempts of trying to find a i could really use some help. The actual value of a is -0.233 or part there of. Here is my best attempt, i cant see where i went wrong.

..
[1.] refers to equation #1.

Here is what I did:

1. [1.] - [3.] = [13] that eliminates the variable c

2. Plug in the term for b from [4.] into the equation [13]. Calculate a = -0.2326422289

3. Plug in this value into [4.]. Calculate b = 9.941429035

4. Plug in the values of a and b into [2.]. Calculate x = 21.36634669

5. Plug in the values of a and b into [1.]. Calculate c = -71.20600969

Please check my arithmetic. I'm a master of desaster if I have to use such unusual numbers.
Reply With Quote
The following users thank earboth for this useful post:
Donate to MHF
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off
Forum Jump


All times are GMT -7. The time now is 04:19 PM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2009, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.2.0 ©2008, Crawlability, Inc.
©2005 - 2009 Math Help Forum


Math Help Forum is a community of maths forums with an emphasis on maths help in all levels of mathematics.
Register to post your math questions or just hang out and try some of our math games or visit the arcade.