Question

question 7
factor the following trinomial.
$a^2 + 8a + 15$
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question 8
factor the following trinomial.
$r^2 - 4r - 21$
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Explanation:

Step1: Find pair for sum 8, product 15

We need two numbers that add to 8 and multiply to 15: 3 and 5.

Step2: Factor the first trinomial

$a^2 + 8a + 15 = (a+3)(a+5)$

Step3: Find pair for sum -4, product -21

We need two numbers that add to -4 and multiply to -21: 3 and -7.

Step4: Factor the second trinomial

$r^2 - 4r - 21 = (r+3)(r-7)$

Answer:

1. $(a+3)(a+5)$
2. $(r+3)(r-7)$