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2x - 7y = 2 and 3x + y = -20 addition/elimination

User Froyke
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2 Answers

2 votes

Final answer:

The question requires solving a system of equations using addition/elimination. After manipulating the second equation and combining them, x is found to be -6. Substituting x into one of the original equations then gives y as -2.

Step-by-step explanation:

The question involves solving a system of linear equations using the addition/elimination method. To solve the given equations 2x - 7y = 2 and 3x + y = -20, we need to manipulate the equations in such a way that adding them will eliminate one of the variables.

First, we can multiply the second equation by 7 to make the coefficients of y equal and opposite in sign:


7(3x + y) = 7(-20)

21x + 7y = -140


Now add the new equation to the first one:


(2x - 7y) + (21x + 7y) = 2 - 140

23x = -138


We can now solve for x:

x = -138 / 23
x = -6


Substitute x back into one of the original equations to solve for y, for example, the second equation:


3(-6) + y = -20

y = -2

Hence X = -6 and Y = -2.

User Valentino Ru
by
8.7k points
2 votes

Answer:

x = -6, y = -2

Step-by-step explanation:

2x-7y = 2

3x + y = -20

We need to cancel out either x or y to solve the equation. I'll cancel out x first

3(2x-7y = 2)

-2(3x+y=-20)

___________

6x-21y = 6

-6x -2y = 40

____________

-23y = 46

y = -2

Plug the value for y in one of the 2 equations to solve for x

2x -7(-2) = 2

2x+14=2

2x = -12

x=-6

User Sanka
by
8.5k points

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