Solving for d1 & d2 with given equations

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Homework Help Overview

The discussion revolves around solving for the vectors d1 and d2 using the equations d1 + 8d2 = 5d3 and d1 - d2 = 9d3, with d3 defined as a vector. Participants are exploring methods to isolate d1 and d2 based on these equations.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to substitute the equations but reports difficulties in obtaining the correct values for d1 and d2. Some participants suggest showing specific examples of the errors encountered. Others propose methods such as subtraction of the equations to simplify the problem.

Discussion Status

The discussion is ongoing, with participants providing guidance on potential approaches, including substitution and subtraction methods. There is no explicit consensus on the best method yet, and multiple interpretations of the equations are being explored.

Contextual Notes

Participants are working within the constraints of the given equations and the vector definition of d3. There is an indication of confusion regarding the manipulation of the equations, particularly in terms of combining or rearranging them.

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Given d1 + 8d2 = 5d3, d1 - d2 = 9d3, and d3 = 2 i + 4 j, what are the following vectors?

(a) d1 =
(b) d2 =

I keep trying to do substituting equations, but I am getting them wrong, and help?
 
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You'll need to show an example of how you are getting them wrong before anyone can help. It's actually a pretty easy problem.
 
easy, fooled me then
D3=2i+4j
d1=5d3-8d2
d2=-9d3+d1

so i am trying to combine these to give me the value of either only d1 or only d2, and no matter how I mess with them, I can't seem to be able to do it.

d1=10i+20j-18j-36j-d1 so I can't do this, plus its wrong

idk did I mess up the subbing eq's?
 
Try subtracting the first two equations from each other. Doesn't that get rid of d1?
 
could you be a a little more specific and in dx-dy and do you mean set equal or subtract?
 
You could do either a substitution or a subtraction. You will either see that d1 = blah, or eqn1 - eqn2 = something*d2 = blap - bleh.
 
Last edited:
I mean (d1+8d2)-(d1-d2)=5d3-9d3. What's that?
 

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