Solve the system of linear equations

frctl

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40x1+ 30x2= 24
20x1+ 15x2= -14
 

Subhotosh Khan

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40x1+ 30x2= 24
20x1+ 15x2= -14
What are your thoughts?

Where are you stuck?

You have 100+ posts -- you should know that you need to show us your efforts before we put in our efforts to help you solve your problem.
 

frctl

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I think I must solve by back substitution but I think I am must reduce first
 

Subhotosh Khan

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I think I must solve by back substitution but I think I am must reduce first
Go ahead and try and show your work.

We will start discussion from there.
 

frctl

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I don't see any common factor, can I instead add both equations together?
 

Subhotosh Khan

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I don't see any common factor, can I instead add both equations together?
What method you are trying to apply? - matrix? substitution? elimination? something else?
 

frctl

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I can use any, I am asked simply to solve
 

Subhotosh Khan

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frctl

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40x1+ 30x2= 24
20x1+ 15x2= -14

Multiply equation 2 by 2
40x1+ 30x2= 24
40x1 + 30x2 = -28

Adding both equations gives me -4
 

Subhotosh Khan

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40x1+ 30x2= 24
20x1+ 15x2= -14

Multiply equation 2 by 2
40x1+ 30x2= 24
40x1 + 30x2 = -28

Adding both equations gives me -4................................Incorrect
Try again!

However, addition will not guide you towards a valid conclusion.
 

frctl

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What can I do in the place?

Maybe I can isolate x1
 

Subhotosh Khan

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What can I do in the place?
Did you figure out:

What mistake did you make in your response #9?

You are adding two sets of equations - the result should an equation (not a number).

First correct your mistake - then we will discuss "what you can do in its place".
 

frctl

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40x1+ 30x2= 24
20x1+ 15x2= -14

Multiply equation 2 by 2
40x1+ 30x2= 24
40x1 + 30x2 = -28
 

Subhotosh Khan

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40x1+ 30x2= 24
20x1+ 15x2= -14

Multiply equation 2 by 2
40x1+ 30x2= 24
40x1 + 30x2 = -28
Next - what operation did you conduct?
 

frctl

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I isolated x1
x1 = (-30x2+24)/40
 

Subhotosh Khan

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frctl

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I can't edit this response anymore.
Is there another mistake?
 

Subhotosh Khan

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frctl

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I don't understand what do you mean
 

Subhotosh Khan

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I don't understand what do you mean
What part of my statement you do not understand?

While writing response #9 - you conducted some mathematical steps and you made a conclusion (which was incorrect).

I would like for you to "find" your mistake and correct your conclusion (in a new post - since you cannot edit it).
 
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