What equation can pair with x +2y=5 to create an inconsistent system a. 2x+4y=3 b.5x+2y=3 c.6x+12y=30 d.3x+4y=8

A

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Step-by-step explanation:

Try to solve using simultaneous equations with each answer given.  

x + 2y = 5  

x = 5 - 2y  

Plug this into each equation  

A 2(5 - 2y) + 4y = 3  

10 - 4y + 4y = 3  

10 = 3 in consistent  

B 5(5 - 2y) + 2y = 3  

25 - 10 y + 2y = 3  

25 - 8y = 3  

8y = 22  

y = 2.75  

Using original equation solve for x  

5x + 2(2.75) = 3  

5x + 5.5 = 3  

5x = -2.5  

x = -0.5  

Using original equation,  

(-0.5) + 2 (2.75) = 5  

-0.5 + 5.5 = 5 consistent  

C 6x + 12y = 30  

6(5 - 2y) + 12y = 30  

30 - 12y + 12 y = 30 consistent for every value of y  

D 3(5 - 2y) + 4y = 8  

15 - 6y + 4y = 8  

- 2y = -7  

y = 3.5  

x = 5 - 2y  

x = 5 - 7  

x = -2  

Solving for x  

3(-2) + 4(3.5) = -6 + 14 = 8 consistent  

So A is the correct answer

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step-by-step explanation: