How do you evaluate \frac{3x ^ { 2} - 8x + 4}{x - 2}3x28x+4x2?

1 Answer
Dec 8, 2017

color(blue)(3x-2)3x2

Explanation:

We need to evaluate color(red)((3x^2-8x+4)/(x-2))3x28x+4x2

We will treat the given rational expression as follows:

Consider the Numerator first

color(red)(3x^2-8x+4)3x28x+4 .. color(red)(Expression.1)..Expression.1

Evidently, this is a quadratic expression

We can factorize this quadratic expression:

To factor this quadratic expression, we will follow the procedure given below:

color(green)(Step.1)Step.1

We must split the coefficient of middle term into two numbers , such that when we add them we get the middle term, and when we multiply them we must get the product of the coefficient of the x^2 termx2term and the constant,

Note that the product of the coefficient of the x^2 termx2term and the constant is (12)(12),

color(green)(Step.2)Step.2

The two numbers are: color(blue)(-6 and -2)6and2

When we add ( - 6) and ( -2 ) we get (- 8)(8) and when we multiply the two values ( - 6) and ( -2 ) we get ( 3 X 4 = 12 )

Now, we write our .. color(red)(Expression.1)..Expression.1 as follows:

color(blue)(3x^2-2x - 6x+4)3x22x6x+4 .. color(red)(Expression.2)..Expression.2

color(green)(Step.3)Step.3

In this step, we break our .. color(red)(Expression.2)..Expression.2 into groups:

color(blue)(rArr (3x^2 - 2x) + (-6x +4))(3x22x)+(6x+4)

Factor out color(green)(x)x from color(blue)((3x^2 - 2x)(3x22x) to obtain color(blue)(rArr x*(3x - 2) )x(3x2)

Factor out color(green)(-2)2 from color(blue)((-6x +4)(6x+4) to obtain color(blue)(rArr -2*(3x -2) )2(3x2)

color(green)(Step.4)Step.4

Using color(green)(Step.3)Step.3 we can factor out the common term color(blue)((3x-2)(3x2) and write the factors of our quadratic expression:

color(blue)(rArr (3x -2) * (x - 2)(3x2)(x2)

color(green)(Step.5)Step.5

In this step we can rewrite our Numerator color(red)(3x^2-8x+4)3x28x+4 as

color(blue)(rArr (3x -2) * (x - 2)(3x2)(x2) .. color(red)(Expression.3)..Expression.3

color(green)(Step.6)Step.6

In this step, we will work on our given expression color(red)((3x^2-8x+4)/(x-2))3x28x+4x2

We can now write the above rational expression, using color(red)(Expression.3)Expression.3 as follows:

color(blue)( {(3x -2) * (x - 2))/((x-2))}(3x2)(x2)(x2)

On simplification we get,

color(blue)( {(3x -2) * cancel((x - 2)))/cancel((x-2))}

Hence, color(blue)(3x-2) is our final answer.

I Hope this helps.