High School

Solve [tex]4x^2 + 8x + 3 = 0[/tex] for [tex]x[/tex].

A. [tex]x = -8.5[/tex]; [tex]x = -7.5[/tex]

B. [tex]x = 7.5[/tex]; [tex]x = 8.5[/tex]

C. [tex]x = 0.5[/tex]; [tex]x = 1.5[/tex]

D. [tex]x = -1.5[/tex]; [tex]x = -0.5[/tex]

Answer :

To solve the quadratic equation [tex]\(4x^2 + 8x + 3 = 0\)[/tex], we can use the quadratic formula. The formula is:

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

Here, the coefficients from the equation are:
- [tex]\( a = 4 \)[/tex]
- [tex]\( b = 8 \)[/tex]
- [tex]\( c = 3 \)[/tex]

First, we calculate the discriminant, [tex]\( b^2 - 4ac \)[/tex]:

[tex]\[ b^2 = 8^2 = 64 \][/tex]

[tex]\[ 4ac = 4 \times 4 \times 3 = 48 \][/tex]

So, the discriminant is:

[tex]\[ 64 - 48 = 16 \][/tex]

Since the discriminant is positive, the equation has two real and distinct solutions.

Now, we can find the values of [tex]\( x \)[/tex] using the quadratic formula:

1. Find [tex]\(\frac{-b + \sqrt{b^2 - 4ac}}{2a}\)[/tex]:

[tex]\[ x_1 = \frac{-8 + \sqrt{16}}{8} = \frac{-8 + 4}{8} = \frac{-4}{8} = -0.5 \][/tex]

2. Find [tex]\(\frac{-b - \sqrt{b^2 - 4ac}}{2a}\)[/tex]:

[tex]\[ x_2 = \frac{-8 - \sqrt{16}}{8} = \frac{-8 - 4}{8} = \frac{-12}{8} = -1.5 \][/tex]

Therefore, the solutions are [tex]\( x = -0.5 \)[/tex] and [tex]\( x = -1.5 \)[/tex].

The correct option is:
(D) [tex]\( x = -1.5 \)[/tex]; [tex]\( x = -0.5 \)[/tex]