Question

Find the roots of the function

of the function
f(x)= x^2 + 81

A. X = -81i, 81i

B. X = -81, 81

C. X= -9, 9

D. X= -9i, 9i

Answer 1

`f(x)=x^2+81\\\\x^2+81=0\qquad|-81\\\\x^2=-81\to x=\pm√(-81)\\\\x=-√((81)(-1))\ \vee\ x=√((81)(-1))\\\\x=-√(81)\cdot√(-1)\ \vee\ x=√(81)\cdot√(-1)\\\\\boxed{x=-9i\ \vee\ x=9i}\\\\Answer:\ D.`