What are the roots of the equation 16x2 + 40x + 27 = 0 in simplest a + bi form?

9514 1404 393

  -5/4 +i(√2)/4 and -5/4 -i(√2)/4

Step-by-step explanation:

I find simplest form to be easier to get to if the leading coefficient is 1. Dividing by 16, we have ...

  x^2 +5/2x +27/16 = 0

Completing the square by adding and subtracting the square of half the x-coefficient, we get ...

  (x^2 +5/2x +25/16) +27/16 -25/16 = 0

  (x +5/4)^2 = 2/16

Subtracting 2/16, taking the square root, and subtracting 5/4 gives ...

  x +5/4 = ±√(-2/16)

  x = -5/4 ±i(√2)/4

The roots are -5/4 +i(√2)/4 and -5/4 -i(√2)/4.

c-4 is the final answer! : )