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4 votes
Y=4x-5
-x-8y=7

A.(-6,1)
B.(1,1)
C.(-1,1)
D.(1,-1)

User Egyamado
by
4.8k points

1 Answer

6 votes

Answer:

D. (1,-1)

Explanation:

The only answer choice that satisfies the first equation is (x, y) = (1, -1).

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Since you have an expression for y, you can solve the system using substitution:

-x -8(4x-5) = 7

-x -32x +40 = 7 . . .eliminate parentheses

-33x = -33 . . . . . . . subtract 40

x = 1 . . . . . . . . . . . . divide by -33 . . . . matches choices B and D

Then using the equation for y, we have ...

y = 4(1) -5 = -1 . . . . . matches choice D

The solution is (x, y) = (1, -1).

User Olga Budnik
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4.8k points