18z + 9y - 4z + 15 - 8 + y - 2
1 answer:
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Answer:
y = 5, -4
Step-by-step explanation:
To solve proportions you cross-multiply.
Now that we have 8 = y^2 - y - 12, we must make the entire trinomial equal to 0 by subtracting 8 from both sides.
y^2 - y - 20 = 0
Factor the trinomial.
(y - 5)(y + 4) = 0
Make both factors equal to 0 to solve for both values of y.
- y - 5 = 0 --> y = 5
- y + 4 = 0 --> y = -4
y = 5, -4