Question

24 PTS!!!!!!1

Which ordered pair is the best estimate for the solution of the system of equations?y=−12x+4
y=12x−3

A(7, 0)

B(7, 1)

C(7.5, 0.5)

D(7, 0.5)

Answer 1

D (7, 0.5)

Explanation:

The equations must be interpreted to be ...

• y = -1/2x +4
• y = 1/2x -3

A graph shows the solution to be (7, 0.5), matching selection D.

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You can add the two equations together to get ...

(y) +(y) = (-1/2x +4) + (1/2x -3)

2y = 1 . . . . . simplify

y = 1/2 . . . . .divide by 2

It can be convenient to use the second equation to find x.

1/2 = 1/2x - 3

1 = x - 6 . . . . . . multiply by 2

7 = x . . . . . . . . . add 6

The solution is (x, y) = (7, 0.5). . . . . matches selection D.