Looking for answers? Westonci.ca is your go-to Q&A platform, offering quick, trustworthy responses from a community of experts. Join our Q&A platform and connect with professionals ready to provide precise answers to your questions in various areas. Explore comprehensive solutions to your questions from knowledgeable professionals across various fields on our platform.

Quadratic Formula (Rational Solutions)

Question:

Use the quadratic formula to solve. Express your answer in simplest form.

[tex]\[ -b^2 - 18b - 8 = -6b^2 \][/tex]

Answer Attempt 1 out of 2:


Sagot :

Certainly! Let's solve the quadratic equation step-by-step.

### Step 1: Rearrange the equation \(\ -b^2-18b-8=-6b^2\)

Move all terms to one side of the equation to set it to 0:
[tex]\[ -b^2 - 18b - 8 \ + \ 6b^2 = 0 \][/tex]

### Step 2: Combine like terms

[tex]\[ -b^2 \ + \ 6b^2 - 18b - 8 = 0 \][/tex]

[tex]\[ 5b^2 - 18b - 8 = 0 \][/tex]

Now, we have a standard quadratic equation of the form \( ax^2 + bx + c = 0 \), where \( a = 5 \), \( b = -18 \), and \( c = -8 \).

### Step 3: Calculate the discriminant

The discriminant \(\Delta\) of a quadratic equation \( ax^2 + bx + c = 0 \) is given by:
[tex]\[ \Delta = b^2 - 4ac \][/tex]

Plugging in the values of \(a\), \(b\), and \(c\):
[tex]\[ \Delta = (-18)^2 - 4 \cdot 5 \cdot (-8) \][/tex]
[tex]\[ \Delta = 324 + 160 \][/tex]
[tex]\[ \Delta = 484 \][/tex]

### Step 4: Solve using the quadratic formula

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

Using the values \(a = 5\), \(b = -18\), and \(\Delta = 484\):

Calculate the first root (\(x_1\)):
[tex]\[ x_1 = \frac{-(-18) + \sqrt{484}}{2 \cdot 5} \][/tex]
[tex]\[ x_1 = \frac{18 + 22}{10} \][/tex]
[tex]\[ x_1 = \frac{40}{10} \][/tex]
[tex]\[ x_1 = 4.0 \][/tex]

Calculate the second root (\(x_2\)):
[tex]\[ x_2 = \frac{-(-18) - \sqrt{484}}{2 \cdot 5} \][/tex]
[tex]\[ x_2 = \frac{18 - 22}{10} \][/tex]
[tex]\[ x_2 = \frac{-4}{10} \][/tex]
[tex]\[ x_2 = -0.4 \][/tex]

### Step 5: The solutions

The two rational solutions to the quadratic equation \( 5b^2 - 18b - 8 = 0 \) are:
[tex]\[ b = 4.0 \quad \text{and} \quad b = -0.4 \][/tex]

Therefore, the solutions are:
[tex]\[ b = 4.0 \][/tex]
[tex]\[ b = -0.4 \][/tex]