Question

hi! can anyone help me pls?

Answer 1

Answer:

Option B, -4 and 4

Step-by-step explanation:

Step 1:  Subtract 15 from both sides

y^2 - 1 - 15 = 15 - 15

y^2 - 16 = 0

Step 2:  Factor

y^2 - 16

(y + 4)(y - 4)

Step 3:  Find the solutions

y + 4 - 4 = 0 - 4 and y - 4 + 4 = 0 + 4

y = -4 and y = 4

Answer:  Option B, -4 and 4

Answer 2

Answer:

-4 and 4

Step-by-step explanation:

All you need to do is solve for y

$y^{2} - 1 = 15$ (plus 1 to both sides)

$y^{2} = 16$ (take square root of 16)

$y = \sqrt{16}$

$y = +-4$ (whenever you to the root of a perfect square you want the positive and negative root)

To double check if your answer is right: plug in -4 and +4 in as y and see if it equals 15

1. $(4)^{2} - 1 =15$

$16-1 = 15\\15= 15$

(positive 4 checks out)

2. $(-4)^{2} - 1 = 15$

$16 - 1 = 15\\15 = 15$

( negative 4 checks out)