Question

find the roots of the polynomial equation: -x^3+5x^2-11x+55=0

Answer 1

familiar with rational root theorem ?

Answer 2

no im not

Answer 3

okie we can do this problem without that also :)

do this :-
factor GCF from first two terms
factor GCF from last two terms

Answer 4

ok i have that done

Answer 5

\(-x^3+5x^2-11x+55 =0 \)
--------------- --------------

Answer 6

wat do you get after you factor the GCFs ?

Answer 7

x^2 and 5 right?

Answer 8

\(-x^3+5x^2-11x+55=0 \)

\(-x^2(x- 5) -11(x-5)=0 \)

Answer 9

you may factor like above

Answer 10

next see that, you \((x-5)\) is common again, so factor that out aswell

Answer 11

\(-x^2(x- 5) -11(x-5)=0 \)

\((x- 5)(-x^2-1)=0 \)

Answer 12

you with me so far ? :)

Answer 13

yes i am

Answer 14

\(-x^2(x- 5) -11(x-5)=0 \)

\((x- 5)(-x^2-1)=0 \)

\(x-5 = 0\) or \(-x^2-11 = 0\)

\(x = 5\) or \(x^2 = -11\)

\(x = 5\) or \(x = \pm i \sqrt{11}\)

Answer 15

so the roots are : \(5, i \sqrt{11}. -i\sqrt{11}\)

Answer 16

Sweet i go it thanks

Answer 17

glad to hear ! yw !!