contestada

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

Respuesta :

gmany

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

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