Which value of x satisfies both -9x + 4y = 8 and -3x - y = 4 given the same value of y?

Solution:

Solving the two equations simultaneously we have:

-9x + 4y = 8 --- (1)

-3x - y = 4 --- (2)

Multiply 2 by 3 and subtract from (1) as shown below

-9x + 4y = 8
-9x - 3y = 12
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0 + 7y = - 4

7y = -4

y = -4/7

Substituting the value of y in equation 2 we get the value of x.

-3x - (- 4/7) = 4

-3x + 4/7 = 4

-3x = 4 - 4/7

-3x = 24/7

x = -8/7

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Which value of x satisfies both - 9x + 4y = 8 and - 3x - y = 4 given the same value of y?

Summary:

The value of x satisfies both -9x + 4y = 8 and -3x - y = 4 is x = -8/7 gives the same value of y.