Question

Using the given zero, find all other zeros of f(x).

-2i is a zero of f(x) = x^4 - 45x^2 - 196

a) 2i, 14i, -14i
b) 2i, 7, -7
c) 2i, 14, -14
d) 2i, 7i, -71

Answer 1

hello :
answer : a
because : f(2i) = (2i)^4 -45(2i)² -196 = 16(1)-45(-4)-196...... ( i²=-1)
= 16+180 -196 =196-196 =0
same solution : f(14i)=f(-14i)=0