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Unformatted text preview: tute this into the second equation. 2 x + 3 ( 3x - 7 ) = 1 This is an equation in x that we can solve so let’s do that. 2 x + 9 x - 21 = 1
11x = 22
x=2 So, there is the x portion of the solution.
Finally, do NOT forget to go back and find the y portion of the solution. This is one of the more
common mistakes students make in solving systems. To so this we can either plug the x value
into one of the original equations and solve for y or we can just plug it into our substitution that
we found in the first step. That will be easier so let’s do that. y = 3 x - 7 = 3 ( 2 ) - 7 = -1
So, the solution is x = 2 and y = -1 as we noted above.
[Return to Problems] (b) 5x + 4 y = 1
3x - 6 y = 2 With this system we aren’t going to be able to completely avoid fractions. However, it looks like
if we solve the second equation for x we can minimize them. Here is that work. 3x = 6 y + 2
x = 2y +
3 Now, substitute this into the first equation and solve the resulting equation for y. 2ö
5ç 2 y + ÷ + 4 y = 1
10 y + + 4...
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This note was uploaded on 06/06/2012 for the course ICT 4 taught by Professor Mrvinh during the Spring '12 term at Hanoi University of Technology.
- Spring '12