Answer:
x =-5± 2i sqrt(14)
Step-by-step explanation:
x^2 + 10x= -81
Take the coefficient of x and divide by 2
10/2 = 5
Square it
5^2 =25
add to each side
x^2 + 10x+25 = -81+25
( x+5) ^2 = -56
Take the square root of each side
sqrt(( x+5) ^2) =± sqrt(-56)
x+5 = ± sqrt(-1) sqrt(4*14)
x+5 =± i sqrt(4)sqrt(14)
x+5 =± i 2 sqrt(14)
Subtract 5 from each side
x+5-5 =-5± i 2 sqrt(14)
x =-5± 2i sqrt(14)
