Question

question 17
factor the following.
$y^2 - 49$
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question 18
factor the following.
$2a^2 - 18$
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Explanation:

Question 17 Step1: Recognize difference of squares

$y^2 - 49 = y^2 - 7^2$

Question 17 Step2: Apply difference of squares formula

$a^2 - b^2=(a-b)(a+b)$, so $y^2 - 7^2=(y-7)(y+7)$

Question 18 Step1: Factor out the GCF

$2a^2 - 18 = 2(a^2 - 9)$

Question 18 Step2: Recognize difference of squares

$a^2 - 9 = a^2 - 3^2$

Question 18 Step3: Apply difference of squares formula

$a^2 - 3^2=(a-3)(a+3)$, so $2(a^2 - 3^2)=2(a-3)(a+3)$

Answer:

Question 17: $(y-7)(y+7)$
Question 18: $2(a-3)(a+3)$