SOLUTION: whats x and y for 8x+7y=-11 and 4x-3y=14?

Question 967533: whats x and y for 8x+7y=-11 and 4x-3y=14?
Answer by ikleyn(52786) (Show Source): You can put this solution on YOUR website!

You need to solve the system of two linear equations in 2 unknowns

Multiply the second equation by 2 and then distract from the first equation. You will get

8x + 7y = -11,
-
8x - 6y = 28
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      13y = 28 + 11 = 39.

Hence, y = = 3.

Now, substitute the found value of y = 3 into the either equation of your original system, for example, into the first equation. You will get

8x +7*3 = -11,   or

8x + 21 = -11,   or

8x = -11 - 21 = -32.

Hence, x = = -4.

Answer. The solution of the system is x = -4, y = 3.

We applied here the Elimination method.

For solving systems of two linear equations in three unknowns see the lessons
    - Solution of the linear system of two equations in two unknowns by the Substitution method,
    - Solution of the linear system of two equations in two unknowns by the Elimination method,
    - Solution of the linear system of two equations in two unknowns using determinant,
    - Geometry interpretation of the linear system of two equations in two unknowns and
    - Solving word problems using linear systems of two equations in two unknowns.

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