Questions: Solve the equation: (16 r^2-8 r-11=0). Fully simplify your answer, including any non-real solutions.
(r=)
Transcript text: Review for Test 2
Score: 8.44/10
Answered: $8 / 10$
Question 10
Solve the equation: $16 r^{2}-8 r-11=0$. Fully simplify your answer, including any non-real solutions.
$r=$
Question Help:
Video
Submit Question
Solution
Solution Steps
To solve the quadratic equation \(16r^2 - 8r - 11 = 0\), we can use the quadratic formula, which is given by \(r = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\). Here, \(a = 16\), \(b = -8\), and \(c = -11\). We will calculate the discriminant \(b^2 - 4ac\) to determine the nature of the roots and then apply the quadratic formula to find the solutions.
Step 1: Identify the Coefficients
The given quadratic equation is \(16r^2 - 8r - 11 = 0\). Here, we identify the coefficients as follows:
\(a = 16\)
\(b = -8\)
\(c = -11\)
Step 2: Calculate the Discriminant
We calculate the discriminant using the formula \(D = b^2 - 4ac\):
\[
D = (-8)^2 - 4 \cdot 16 \cdot (-11) = 64 + 704 = 768
\]
Step 3: Apply the Quadratic Formula
Using the quadratic formula \(r = \frac{-b \pm \sqrt{D}}{2a}\), we find the roots:
\[
r_1 = \frac{-(-8) + \sqrt{768}}{2 \cdot 16} = \frac{8 + \sqrt{768}}{32}
\]
\[
r_2 = \frac{-(-8) - \sqrt{768}}{2 \cdot 16} = \frac{8 - \sqrt{768}}{32}
\]
Calculating the square root:
\[
\sqrt{768} \approx 27.7128
\]
Now substituting back into the equations for \(r_1\) and \(r_2\):
\[
r_1 = \frac{8 + 27.7128}{32} \approx \frac{35.7128}{32} \approx 1.1160
\]
\[
r_2 = \frac{8 - 27.7128}{32} \approx \frac{-19.7128}{32} \approx -0.6160
\]
Final Answer
The solutions to the equation \(16r^2 - 8r - 11 = 0\) are:
\[
\boxed{r_1 \approx 1.1160, \quad r_2 \approx -0.6160}
\]