Solve 4x^2−9x−34=0 using the quadratic formula. Write answers in decimal form as needed and give the lesser value first.

1 answer

To solve the quadratic equation \( 4x^2 - 9x - 34 = 0 \) using the quadratic formula, we use the formula:

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

where \( a = 4 \), \( b = -9 \), and \( c = -34 \).

First, we need to calculate the discriminant, \( b^2 - 4ac \):

\[ b^2 = (-9)^2 = 81 \] \[ 4ac = 4 \cdot 4 \cdot (-34) = -544 \]

Now, calculate the discriminant:

\[ b^2 - 4ac = 81 - (-544) = 81 + 544 = 625 \]

Since the discriminant is positive, we will have two real solutions. Now, we can substitute \( a \), \( b \), and the discriminant into the formula:

\[ x = \frac{-(-9) \pm \sqrt{625}}{2 \cdot 4} \] \[ x = \frac{9 \pm 25}{8} \]

Now, we will calculate the two possible values for \( x \):

  1. For the positive case (\( + \)): \[ x_1 = \frac{9 + 25}{8} = \frac{34}{8} = 4.25 \]

  2. For the negative case (\( - \)): \[ x_2 = \frac{9 - 25}{8} = \frac{-16}{8} = -2 \]

Thus, the two solutions are \( x_1 = 4.25 \) and \( x_2 = -2 \).

Writing them in decimal form with the lesser value first, we have:

\[ \boxed{-2} \quad \text{and} \quad \boxed{4.25} \]