Question

what is the value of the y-coordinate of solution to the system of equations x-2y=1 ; x+4y=7​

Answer 1

// Solve equation [1] for the variable x

[1] x = 2y + 1

// Plug this in for variable x in equation [2]

[2] -(2y+1) + 4y = -7

[2] 2y = -6

// Solve equation [2] for the variable y

[2] 2y = - 6

[2] y = - 3

// By now we know this much :

x = 2y+1

y = -3

// Use the y value to solve for x

x = 2(-3)+1 = -5

{x,y} = {-5,-3}

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Answer 2

Answer:

so in this question

7x−2y=1

3x+4y=15

so first multiply the first equation by 2

We get 14x−4y=2

now add the first and second equations

14x−4y+3x+4y=15+2

17x=17

so x=1

put x in any equation get y

y=3

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