Question

write a polynomial function with rational coefficients so that P(x)=0 has the given roots : 3i +9

Answer 1

do u know how to do this

Answer 2

kind of, i've only done it like once tho

Answer 3

what would you do

Answer 4

do you know?

Answer 5

the function is just like a polynomial equation right?

Answer 6

yes

Answer 7

well i would try to work it backwards from the quadratic formula but idk if thats right

Answer 8

no u have to do something lie (x-3i) (x+3i) that thing

Answer 9

oh factoring?

Answer 10

yes

Answer 11

can u help now

Answer 12

please help its a factoring problem

Answer 13

well if its factoring then do x*x, x*3i, -3i*x, -3i*x

Answer 14

notice that there is only one root... 3i +9

Answer 15

rational coefficients so that P(x)=0 has the given roots : 3i +9

the rational part means that the roots come in complex conjugate pairs
the other root is 9-3i (you negate the imaginary part)
so your factored polynomial is
( x -(9+3i))*(x- (9-3i))

Answer 16

yes so can someone show me how to do it

Answer 17

and what would that give you

Answer 18

when multiplied

Answer 19

f(x)= ( x -(9+3i))*(x- (9-3i))
is technically the answer. They may want you to expand it (multiply it out)

Answer 20

yes multiply it out please

Answer 21

see
http://www.khanacademy.org/math/algebra/polynomials/v/multiplying-binomials

Answer 22

wait does it give u x^2-18x+90

Answer 23

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