Write a completely simplified rational expression that represents the exchange rate Salma will receive in dollars per euro. Explain how you came up with your expression.

Respuesta :

The exchange rate that She will receive is an algebraic expression

The exchange rate that Salma will receive in dollars per euro is [tex]\frac{12x - 9}{4x -6}[/tex]

How to determine the exchange rate

The amount of dollars with Salma is given as:

[tex]Dollar = \frac{12x^2 + 15x - 18}{2x^2 + 14x + 20}[/tex]

The amount of Euro she can buy is:

[tex]Euro = \frac{2x^2 -x-3}{x^2 + 6x +5}[/tex]

Let the exchange rate be r.

So, we have:

[tex]Dollar * \frac 1r = Euro[/tex]

The equation becomes

[tex]\frac{12x^2 + 15x - 18}{2x^2 + 14x + 20}* \frac 1r = \frac{2x^2 -x-3}{x^2 + 6x +5}[/tex]

Factorize the expressions

[tex]\frac{3(x + 2)(4x - 3)}{2(x + 5)(x +2)}* \frac 1r = \frac{(x +1)(2x -3)}{(x + 5)*x + 1)}[/tex]

Cancel out the common factors

[tex]\frac{3(4x - 3)}{2}* \frac 1r = \frac{(2x -3)}{1}[/tex]

Make r the subject

[tex]\frac 1r = \frac{2(2x -3)}{3(4x - 3)}[/tex]

Expand

[tex]\frac 1r = \frac{4x -6}{12x - 9}[/tex]

Make r the subject

[tex]r = \frac{12x - 9}{4x -6}[/tex]

Hence, the exchange rate is [tex]\frac{12x - 9}{4x -6}[/tex]

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