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Consider the equation:

[tex]\[ x^2 = -8x - 7 \][/tex]

1) Rewrite the equation by completing the square.

Your equation should look like [tex]\((x+c)^2 = d\)[/tex] or [tex]\((x-c)^2 = d\)[/tex].

[tex]\[ 9 = (x+4)^2 \][/tex]

2) What are the solutions to the equation?

Choose 1 answer:

A) [tex]\[ x = -4 \pm 3 \][/tex]

B) [tex]\[ x = 4 \pm 3 \][/tex]

C) [tex]\[ x = -4 \pm 9 \][/tex]


Sagot :

Sure, let's solve this step by step.

### 1) Rewrite the equation by completing the square

The original equation given is:
[tex]\[ x^2 + 8x + 7 \][/tex]

To complete the square, follow these steps:

1. Move the constant term to the right side:
[tex]\[ x^2 + 8x = -7 \][/tex]

2. Add and subtract the necessary term to complete the square on the left side:
- Take half the coefficient of [tex]\(x\)[/tex], which is [tex]\(8/2 = 4\)[/tex].
- Square it to get [tex]\(4^2 = 16\)[/tex].
- Add and subtract this square term on the left side of the equation:
[tex]\[ x^2 + 8x + 16 - 16 = -7 \][/tex]

3. Rewrite it in the form of a perfect square on the left side:

[tex]\[ (x + 4)^2 - 16 = -7 \][/tex]

4. Move the constant term ([tex]\(-16\)[/tex]) to the right side:

[tex]\[ (x + 4)^2 = 9 \][/tex]

So, the completed square form of the given equation is:

[tex]\[ 9 = (x + 4)^2 \][/tex]

### 2) What are the solutions to the equation?

Now, we solve the equation:
[tex]\[ (x + 4)^2 = 9 \][/tex]

Taking the square root of both sides, we get:
[tex]\[ x + 4 = \pm \sqrt{9} \][/tex]

This gives us two separate equations to solve:
[tex]\[ x + 4 = 3 \quad \text{or} \quad x + 4 = -3 \][/tex]

Solving both:
1. [tex]\(x + 4 = 3\)[/tex]
[tex]\[ x = 3 - 4 \][/tex]
[tex]\[ x = -1 \][/tex]

2. [tex]\(x + 4 = -3\)[/tex]
[tex]\[ x = -3 - 4 \][/tex]
[tex]\[ x = -7 \][/tex]

So, the solutions to the equation are:
[tex]\[ x = -1 \quad \text{and} \quad x = -7 \][/tex]

However, if we consider the answer format provided, we summarize the steps as:
[tex]\[ x = -4 \pm 3 \][/tex]

Since one value is:
[tex]\[ -4 + 3 = -1 \][/tex]
And the other value is:
[tex]\[ -4 - 3 = -7 \][/tex]

### Final Answer

Choose the correct answer from the provided options:

(A) [tex]\(x = -4 \pm 3\)[/tex]

So the correct answer is:
[tex]\[ \boxed{x = -4 \pm 3} \][/tex]