Question

Write f(x)=x^3+25x in factored form, and find the roots of f( x). The roots of f( x) are:
a. -25, 1, -1
b. 0, 5, -5
c. -25, i, -i
d. 0, 5i, -5i

Answer 1

you can write it as x(x^2+25), and if you want to find its roots set f(x) to be zero. Then, your product will be zero, if x is zero or x^2+25=0, so the roots are x=0, and the other two are +5i and -5i which are the complex zeroes of x^2+25, so correct answer is d

Answer 2

Thanks nenadmatematika!

Answer 3

you're welcome :D