Question

What is the value of the x variable in the solution to the following system of equations?
7x - 2y = 21
4x + y = 57

21
-21
9
-9
8. [6.03] What is the value of the y variable in the solution to the following system of equations?
5x + 4y = 1
4x + 3y = -1

-7
7
9
-9

Answer 1

Have you considered showing your work?

For the first, I might be tempted to multiply the second equation by 2 and then add the two equations.

Answer 2

1.Substitue the value of x to the 2nd eq'n
Substitute the value of y to the 1st eq'n
the value you get will be 9.

2. Standard form: 4x+3y=10; 4x+5y=14;
substitute/eliminate x = -3/4y+5/2
substitute/eliminate y = +2
Solution: x = 1; y = 2;
(x, y) = (1, 2)

Standard form: 5x+4y=1; 4x+3y=-1;
substitute/eliminate x = -4/5y+1/5
substitute/eliminate y = +9
Solution: x = -7; y = 9;
(x, y) = (-7, 9)

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