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Does anyone know why this is the answer

Does anyone know why this is the answer-example-1
User SeanA
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1 Answer

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24 votes

Answer:

h(x) = (x -1)(x -(3 +√2))(x -(3 -√2))

Explanation:

The given cubic is said to have 1 as a zero. That means (x -1) is a linear factor of the equation. Dividing the cubic by that using your favorite method gives a quotient that is the quadratic ...

x^2 -6x +7

We can write this in vertex form by "completing the square":

(x^2 -6x) +7

= (x^2 -6x +9) +7 -9 . . . . . add and subtract (-6/2)^2 = 9

= (x -3)^2 -2

This can be factored as the difference of two squares:

a² -b² = (a -b)(a +b)

Here we have ...

a² = (x-3)² ⇒ a = (x -3)

b² = 2 ⇒ b = √2

Then the linear factors of the quadratic are ...

x^2 -6x +7 = ((x -3) -√)((x -3) +√2)

= (x -(3 +√2))(x -(3 -√2)) . . . . . using the associative property of addition

And the cubic can be factored to linear factors as ...

h(x) = x^3 -7x^2 +13x -7

h(x) = (x -1)(x^2 -6x +7)

h(x) = (x -1)(x -(3 +√2))(x -(3 -√2))

Does anyone know why this is the answer-example-1
User Turbulencetoo
by
3.0k points