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39 votes
39 votes
I want to know hot solve this problem

I want to know hot solve this problem-example-1
User Andrea Sprega
by
2.9k points

2 Answers

17 votes
17 votes

Answer

C

Explanation:


(w^2-9)/(w^2-4w-21) ( factorise numerator and denominator )

w^2 - 9 ← is a difference of squares and factors as

w² - 9 = (w - 3)(w + 3)

w² - 4w - 21

Consider the factors of the constant term (- 21) which sum to give the coefficient of the w- term ( - 4)

The factors are - 7 and + 3 , since

- 7 × + 3 = - 21 and - 7 + 3 = - 4 , then

w² - 4w - 21 = (w - 7)(w + 3)

Then


((w-3)(w+3))/((w-7)(w+3)) ← cancel the common factor (w + 3) on numerator/ denominator

=
(w-3)/(w-7) → C

User Nedim
by
3.0k points
16 votes
16 votes

I think the answer is A but can be simplified as seen in my photo above

I want to know hot solve this problem-example-1
User Frank Boucher
by
2.9k points
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