Answer:
d =±2sqrt(7) i
Step-by-step explanation:
d^2 = -28
Take the square root of each side
sqrt(d^2) = ±sqrt(-28)
d = ±sqrt(-28)
d = ±sqrt(-1)sqrt(28)
We know that sqrt(-1) = i
d =±i*sqrt(4)sqrt(7)
d =±i 2sqrt(7)
