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Solve the system of equations. x + y = 8; y = x2 – 4

(3, 5) and (–4, 12)

(–3, 11) and (4, 4)

(4, 4) and (5, 3)

(12, –4) and (7, 1)

User Richard Hodges
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2 Answers

10 votes
10 votes

Answer:

A. (3, 5) and (–4, 12)

Explanation:

I took the Algebra exam

User Sbaechler
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20 votes
20 votes

Answer:

(3, 5) and (-4, 12)

Explanation:

To solve this system of equations, we'll use the substitution method.

Plug in the given y = x² - 4 into the other equation

x + x² - 4 = 8

Subtract 8 from both sides

x² + x - 4 = 8

- 8 - 8

x² + x - 12 = 0

Factor out the equation

x² + x - 12 = (x + 4)(x - 3) = 0

For the equation to be 0, x will have to equal -4 and 3

Now plug in the new x's into one of the original equations

We'll use y = x² - 4

y = (-4)² - 4 = 16 - 4 = 12

y = 3² - 4 = 9 - 4 = 5

When x = -4, y = 12, so one of the answers is (-4, 12)

When x = 3, y - 5, so one of the answers is (3, 5)

User Markon
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