15. Change the fraction w – 3 / w + 5 into an equivalent fraction with the denominator w^2 + w – 20.


A.w^2 + 7w – 12 / w^2 + w – 20.


B.w^2 – 7 – 12 / w^2 + w – 20


C.w^2 – 7w + 12 / w^2 + w – 20


D.w^2 + 7w + 12 / w^2 + w – 20

Respuesta :

w^2 + w - 20 = (w + 5)(w - 4)

(w - 3)     (w - 4)      w^2 - 7w + 12
---------- * -------- =    ------------------
(w + 5)    (w - 4)        w^2 + w - 20

Answer:

C. [tex]\frac{w^2-7w+12}{w^2+w-20}[/tex]

Step-by-step explanation:

We have been given a fraction [tex]\frac{w-3}{w+5}[/tex] and we are asked to write the equivalent fraction of our given fraction with the denominator  [tex]w^2+w-10[/tex].

First of all we will divide [tex]w^2+w-10[/tex] by [tex]w+5[/tex] to find the expression that we need to multiply with our given fraction to get the denominator [tex]w^2+w-10[/tex]

Let us factor out [tex]w^2+w-10[/tex] by splitting the middle term

[tex]w^2+w-10[/tex]

[tex]w^2+5w-4w-20[/tex]

[tex]w(w+5)-4(w+5)[/tex]

[tex](w+5)(w-4)[/tex]

[tex]\frac{w^2+w-20}{w+5}=\frac{(w+5)(w-4)}{(w+5)}=(w-4)[/tex]

Now we will multiply the numerator and denominator of [tex]\frac{w-3}{w+5}[/tex] by [tex](w-4)[/tex] to find the equivalent fraction.

[tex]\frac{w-3}{w+5}*\frac{(w-4)}{(w-4)}[/tex]

[tex]\frac{(w-3)*(w-4)}{(w+5)*(w-4)}[/tex]

[tex]\frac{w^2-4w-3w+12}{w^2-4w+5w-20}[/tex]

[tex]\frac{w^2-7w+12}{w^2+w-20}[/tex]

Therefore, option C is the correct choice.