Use the quadratic formula to solve the quadratic equation 8x2+5=12x

. Express its solutions in the form a±bi
.(1 point)

1 answer

To solve the quadratic equation \( 8x^2 + 5 = 12x \), we first rearrange it into standard form:

\[ 8x^2 - 12x + 5 = 0 \]

In the standard form \( ax^2 + bx + c = 0 \), we have:

  • \( a = 8 \)
  • \( b = -12 \)
  • \( c = 5 \)

Next, we apply the quadratic formula:

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

Calculating the discriminant \( b^2 - 4ac \):

\[ b^2 = (-12)^2 = 144 \] \[ 4ac = 4 \cdot 8 \cdot 5 = 160 \] \[ b^2 - 4ac = 144 - 160 = -16 \]

Since the discriminant is negative, we will have complex solutions. Now, we substitute \( a \), \( b \), and the discriminant into the quadratic formula:

\[ x = \frac{-(-12) \pm \sqrt{-16}}{2 \cdot 8} \] \[ x = \frac{12 \pm \sqrt{-16}}{16} \]

We can simplify \( \sqrt{-16} \):

\[ \sqrt{-16} = 4i \]

Substituting this back into the formula gives us:

\[ x = \frac{12 \pm 4i}{16} \]

We can simplify this expression further:

\[ x = \frac{12}{16} \pm \frac{4i}{16} \] \[ x = \frac{3}{4} \pm \frac{i}{4} \]

Thus, the solutions to the quadratic equation \( 8x^2 + 5 = 12x \) are:

\[ x = \frac{3}{4} \pm \frac{1}{4}i \]

Final answer:

\[ x = \frac{3}{4} \pm \frac{1}{4}i \]