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The polynomial equation x^3-4x^2+2x+10=x^2-5x-3 has complex roots 3+2i What is the other root? Use a graphing calculator and a system of equations.
a –3
b –1
c 3
d 10

Respuesta :

The other root would be (B) -1

Answer:

The correct option is b.

Step-by-step explanation:

The given expression is

[tex]x^3-4x^2+2x+10=x^2-5x-3[/tex]

Simplify the equation.

[tex]x^3-4x^2+2x+10-x^2+5x+3=0[/tex]

[tex]x^3-5x^2+7x+13=0[/tex]

It is given that 3+2i is a root of the equation and (x-3-2i) is a factor.

By complex conjugate root theorem if a+ib is a root of an equation then a-ib must be the root of the equation.

It means 3-2i is a root of the equation and (x-3+2i) is a factor.

[tex](x-3-2i)(x-3+2i)=(x-3)^2-(2i)^2=x^2-6x+9+4=x^2-6x+13[/tex]

Divide [tex]x^3-5x^2+7x+13=0[/tex] by [tex]x^2-6x+13[/tex], to find the remaining factor.

By the long division method, the quotient is (x+1) and remainder is 0. It means (x+1) is a remaining factor of the given equation. Equate each factor equal to 0, to find the remaining roots.

[tex]x+1=0[/tex]

[tex]x=-1[/tex]

Therefore the correct option is b.

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