Solve {3x+4y=4-8x+y=-8{3x+4y=4-8x+y=-8 for x and y

[sarahlee]

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Section 5 Simultaneous Equations

5) Solve [FONT=MathJax_Size3]{[/FONT][FONT=MathJax_Main]3[/FONT][FONT=MathJax_Math-italic]x[/FONT][FONT=MathJax_Main]+[/FONT][FONT=MathJax_Main]4[/FONT][FONT=MathJax_Math-italic]y[/FONT][FONT=MathJax_Main]=[/FONT][FONT=MathJax_Main]4[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Main]8[/FONT][FONT=MathJax_Math-italic]x[/FONT][FONT=MathJax_Main]+[/FONT][FONT=MathJax_Math-italic]y[/FONT][FONT=MathJax_Main]=[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Main]8[/FONT]{3x+4y=4−8x+y=−8
Correct your answers to 3 decimal places. x = , y = .

 

[Dr.Peterson]

Section 5 Simultaneous Equations

5) Solve [FONT=MathJax_Size3]{[/FONT][FONT=MathJax_Main]3[/FONT][FONT=MathJax_Math-italic]x[/FONT][FONT=MathJax_Main]+[/FONT][FONT=MathJax_Main]4[/FONT][FONT=MathJax_Math-italic]y[/FONT][FONT=MathJax_Main]=[/FONT][FONT=MathJax_Main]4[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Main]8[/FONT][FONT=MathJax_Math-italic]x[/FONT][FONT=MathJax_Main]+[/FONT][FONT=MathJax_Math-italic]y[/FONT][FONT=MathJax_Main]=[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Main]8[/FONT]{3x+4y=4−8x+y=−8 Correct your answers to 3 decimal places. x = , y = .

This didn't come through very well, but it is presumably supposed to be the system

3x+4y=4
−8x+y=−8
​

And I suppose "correct your answers to ..." is supposed to be "Enter you answers, correct to ...". Your computer testing system doesn't appear to be very well designed.

If you haven't learned to solve these, see here. Either substitution or addition should work well.

 

[HallsofIvy]

Assuming this is supposed to be 3x+ 4y= 4, -8x+ y= -8, then I would multiply second equation by -4 to get 32x- 4y= 32. What do you get when you add 3x+ 4y= 4 to that?