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What are the solutions to the equation using the quadratic formula?

[tex]x^2 + 7x + 4 = 0[/tex]

A. [tex]x = \frac{7 \pm \sqrt{33}}{2}[/tex]
B. [tex]x = \frac{-7 \pm \sqrt{65}}{2}[/tex]
C. [tex]x = \frac{-7 \pm \sqrt{33}}{2}[/tex]
D. [tex]x = \frac{7 \pm 3\sqrt{5}}{2}[/tex]


Sagot :

Sure, let's solve the quadratic equation [tex]\(x^2 + 7x + 4 = 0\)[/tex] using the quadratic formula.

The quadratic formula is given by:
[tex]\[ x = \frac{{-b \pm \sqrt{{b^2 - 4ac}}}}{2a} \][/tex]

Here, the coefficients are [tex]\(a = 1\)[/tex], [tex]\(b = 7\)[/tex], and [tex]\(c = 4\)[/tex].

1. Calculate the discriminant:
[tex]\[ \text{Discriminant} = b^2 - 4ac = 7^2 - 4 \cdot 1 \cdot 4 = 49 - 16 = 33 \][/tex]

2. Apply the quadratic formula:
[tex]\[ x = \frac{{-b \pm \sqrt{{\text{Discriminant}}}}}{2a} = \frac{{-7 \pm \sqrt{33}}}{2 \cdot 1} = \frac{{-7 \pm \sqrt{33}}}{2} \][/tex]

Now, let's find the two solutions by separately considering the `plus` and `minus` parts of the formula:

- First solution ([tex]\(x_1\)[/tex]):
[tex]\[ x_1 = \frac{{-7 + \sqrt{33}}}{2} \][/tex]

- Second solution ([tex]\(x_2\)[/tex]):
[tex]\[ x_2 = \frac{{-7 - \sqrt{33}}}{2} \][/tex]

Putting it all together, the solutions to the quadratic equation [tex]\(x^2 + 7x + 4 = 0\)[/tex] are:
[tex]\[ x_1 = \frac{{-7 + \sqrt{33}}}{2} \quad \text{and} \quad x_2 = \frac{{-7 - \sqrt{33}}}{2} \][/tex]

These solutions are approximately [tex]\(-0.628\)[/tex] and [tex]\(-6.372\)[/tex], respectively.

So, the correct answer from the provided options is:
[tex]\[ x = \frac{{-7 \pm \sqrt{33}}}{2} \][/tex]