For these types of problems you need two equations that will mesh together to give you what you want.
Code:
A computer company just bought new suplies. Computers cost $8 and Printers 10$. They ordererd 225 products that came to the price of $1,950. How many of each product was ordered?
So lets take a look at the obvious equations #1
This states that the total number of items equals 255
Equation 2
This states that the total amount spent was 1950, two things were bought, and we multiply the quantity of each by its price.
(realy screwed up pricing, but whatever)
Meshing the two equations we get this:
Code:
C + P = 225
8C + 10P = 1950
C = 225 - P
8C + 10(225 - P) = 225
Basically what we just did was eliminate one variable. Because we can deal with just one, its when they become more numerous than one that it becomes a problem. There are an infinite number of possibilities to satisfy the equation
I'll let you do the solving part, but remember whenever you have more than one variable you need the same number of equations to solve the problem.
There are actualy three ways to combine more than one equation
Sunbstitution:
The method I showed you. We manipulate the equation until we have only one positive variable on one side and then use that equation to substitute for teh chosen variable.
Adition:
If you have two equations like
Code:
3s + 5r = 100
and
6s - 5r =55
you can actually make an equation out of them like this:
Code:
3s + 5r = 100
+ 6s - 5r = 55
_____________
9s +0r = 155
This gives you a 0 for the r value and tells you what s will equal, then its a simple substitution for your known value of s in to either of your original equation to find s
Graphing:
I won't go too in to depth here, but you can graph a pair of equations on a Cartesian plane, their intersect point (x,y) will be the solution to both numbers
I use this when I just need to approximate the needed value.
If you have any questions feel free to PM me or poke me on AIM or MSN. Good luck!
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A Question I Always Come Across
Linear Mode
