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Instructions: Put the equation in standard form (if not already), then solve using the quadratic formula.

[tex]\[
\begin{array}{l}
x^2-3x+7=0 \\
x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}
\end{array}
\][/tex]

In this case, [tex]\(a = 1\)[/tex], [tex]\(b = -3\)[/tex], and [tex]\(c = 7\)[/tex].

[tex]\[
x = \frac{-(-3) \pm \sqrt{(-3)^2 - 4 \cdot 1 \cdot 7}}{2 \cdot 1}
\][/tex]

Simplify to find the values of [tex]\(x\)[/tex].

Sagot :

Sure! Let's solve the quadratic equation [tex]\(x^2 - 3x + 7 = 0\)[/tex] using the quadratic formula. The standard form of a quadratic equation is [tex]\(ax^2 + bx + c = 0\)[/tex], where [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] are constants.

In this equation, we can identify:
- [tex]\(a = 1\)[/tex]
- [tex]\(b = -3\)[/tex]
- [tex]\(c = 7\)[/tex]

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

### Step-by-Step Solution

1. Calculate the Discriminant:
[tex]\[ \text{Discriminant} = b^2 - 4ac \][/tex]
Plugging in the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:
[tex]\[ \text{Discriminant} = (-3)^2 - 4(1)(7) = 9 - 28 = -19 \][/tex]

2. Evaluate the Roots Using the Quadratic Formula:
Since the discriminant is negative ([tex]\(-19\)[/tex]), this means we will have complex (imaginary) roots.
Plugging in the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and the discriminant into the quadratic formula:
[tex]\[ x = \frac{-(-3) \pm \sqrt{-19}}{2(1)} \][/tex]
Simplify:
[tex]\[ x = \frac{3 \pm \sqrt{-19}}{2} \][/tex]

3. Express the Square Root of the Negative Discriminant:
Recall that [tex]\(\sqrt{-19} = i\sqrt{19}\)[/tex], where [tex]\(i\)[/tex] is the imaginary unit.
Thus:
[tex]\[ x = \frac{3 \pm i\sqrt{19}}{2} \][/tex]

Finally, we can write the two solutions as:
[tex]\[ x = \frac{3 + i\sqrt{19}}{2} \quad \text{or} \quad x = \frac{3 - i\sqrt{19}}{2} \][/tex]

So, the solutions to the quadratic equation [tex]\(x^2 - 3x + 7 = 0\)[/tex] are:
[tex]\[ x = \frac{3 + i\sqrt{19}}{2} \quad \text{and} \quad x = \frac{3 - i\sqrt{19}}{2} \][/tex]