Using the quadratic formula to solve [tex]4x^2 - 3x + 9 = 2x + 1[/tex], what are the values of [tex]x[/tex]?

A. [tex]\frac{1 \pm \sqrt{159} i}{8}[/tex]
B. [tex]\frac{5 \pm \sqrt{153} i}{8}[/tex]
C. [tex]\frac{5 \pm \sqrt{103} i}{8}[/tex]
D. [tex]\frac{1 \pm \sqrt{153}}{8}[/tex]



Answer :

To solve the quadratic equation [tex]\(4x^2 - 3x + 9 = 2x + 1\)[/tex], we will first bring all terms to one side of the equation to set it to zero. This will give us the quadratic equation in the standard form [tex]\(ax^2 + bx + c = 0\)[/tex].

Starting with the original equation:

[tex]\[ 4x^2 - 3x + 9 = 2x + 1 \][/tex]

We subtract [tex]\(2x\)[/tex] and 1 from both sides to get:

[tex]\[ 4x^2 - 3x + 9 - 2x - 1 = 0 \][/tex]

This simplifies to:

[tex]\[ 4x^2 - 5x + 8 = 0 \][/tex]

Now, we have a quadratic equation in the form [tex]\(ax^2 + bx + c = 0\)[/tex], where:
- [tex]\(a = 4\)[/tex]
- [tex]\(b = -5\)[/tex]
- [tex]\(c = 8\)[/tex]

Next, we will use the quadratic formula to find the values of [tex]\(x\)[/tex]. The quadratic formula is given by:

[tex]\[ x = \frac{{-b \pm \sqrt{{b^2 - 4ac}}}}{2a} \][/tex]

First, we calculate the discriminant [tex]\(\Delta\)[/tex]:

[tex]\[ \Delta = b^2 - 4ac \][/tex]

Substituting in the values for [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:

[tex]\[ \Delta = (-5)^2 - 4(4)(8) \][/tex]

[tex]\[ \Delta = 25 - 128 \][/tex]

[tex]\[ \Delta = -103 \][/tex]

The discriminant [tex]\(\Delta\)[/tex] is [tex]\(-103\)[/tex], which is negative. This tells us there are no real solutions, but there are two complex solutions. We write the solutions using [tex]\(i\)[/tex], the imaginary unit, where [tex]\(i^2 = -1\)[/tex].

The solutions are:

[tex]\[ x = \frac{{-(-5) \pm \sqrt{{-103}}}}{2 \cdot 4} \][/tex]

[tex]\[ x = \frac{{5 \pm \sqrt{103} \cdot i}}{8} \][/tex]

Thus, the values of [tex]\(x\)[/tex] are:

[tex]\[ x_1 = \frac{5 + \sqrt{103} \cdot i}{8} \][/tex]
[tex]\[ x_2 = \frac{5 - \sqrt{103} \cdot i}{8} \][/tex]

Therefore, the correct answer is:

[tex]\[ \frac{5 \pm \sqrt{103} i}{8} \][/tex]