My Math Forum  

Go Back   My Math Forum > College Math Forum > Linear Algebra

Linear Algebra Linear Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
November 11th, 2012, 12:36 PM   #1
Newbie
 
Joined: Nov 2012

Posts: 5
Thanks: 0

write as an equation?

The following points are part of a table of values for a function.
(0, 2), (1, 4), (2, 10), (3, 2
Represent this function as:
a) an equation
vivalajuicy is offline  
 
November 11th, 2012, 04:49 PM   #2
Math Team
 
Joined: Dec 2006
From: Lexington, MA

Posts: 3,267
Thanks: 407

Re: write as an equation?

Hello, vivalajuicy!

Quote:
The following points are part of a table of values for a function:
[color=beige]. . [/color]

Represent this function as: (a) an equation

I don't have the equation yet, but I have a recurrence.

[color=beige]. . [/color]

soroban is offline  
November 12th, 2012, 12:34 AM   #3
Math Team
 
Joined: Apr 2010

Posts: 2,770
Thanks: 356

Re: write as an equation?

y = 1+3^x
Hoempa is offline  
November 13th, 2012, 06:33 AM   #4
Math Team
 
Joined: Sep 2007

Posts: 2,409
Thanks: 5

Re: write as an equation?

Quote:
Originally Posted by vivalajuicy
The following points are part of a table of values for a function.
(0, 2), (1, 4), (2, 10), (3, 2
Represent this function as:
a) an equation
Four points determine a cubic function so we can write y= ax^3+ bx^2+ cx+ d. Using the values given,
d= 2,
a+ b+ c+ 2= 4 or a+ b+ c= 2
8a+ 4b+ 2c+ 2= 10 or 8a+ 4b+ 2c= 8, and, dividing by 2, 4a+ 2b+ c= 4.
27a+ 9b+ 3c+ 2= 28 or 27a+ 9b+ 3c= 26

If we subtract a+ b+ c= 2 from 4a+ 2b+ c= 4, we get 3a+ b= 2.
If we multiply a+ b+ c= 2 by 3 to get 3a+ 3b+ 3c= 6 and subtract that from 27a+ 9b+ 3c= 26 we get 24a+ 6b= 20 or 12a+ 3b= 10.

If we multiply 3a+ b= 2 by 3 we get 9a+ 3b= 6 and subtracting that from 12a+ 3b= 10, 3a= 4 so a= 4/3.
Now, you can put that back into 3a+ b= 2 to find b, and put those into one of the original equations to find c.

That is a completely different solution from Hoempa's but you have to understand that there can be an infinite number of functions whose graph will go through four given points.
HallsofIvy is offline  
Reply

  My Math Forum > College Math Forum > Linear Algebra

Tags
equation, write



Search tags for this page
Click on a term to search for related topics.
Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
write equation MathNewb42 Applied Math 0 March 12th, 2013 06:53 AM
Write an equation for and solve for x fish262 Algebra 1 March 13th, 2012 06:10 PM
how can i write equation phythagoras1 Applied Math 2 December 24th, 2010 12:54 AM
Write the equation of the tangent lineby (2,2?2) rodjav305 Trigonometry 6 July 6th, 2009 03:31 AM
write an equation minhson1989 Algebra 1 September 1st, 2007 05:15 PM





Copyright © 2017 My Math Forum. All rights reserved.