Math  /  Algebra

QuestionSolve. y38y29y=0y=\begin{array}{l} y^{3}-8 y^{2}-9 y=0 \\ y=\square \end{array} \square (Use a comma to separate answers as needed.)

Studdy Solution

STEP 1

What is this asking? We need to find the values of yy that make the equation y38y29y=0y^3 - 8y^2 - 9y = 0 true. Watch out! Don't forget to check if **zero** is a solution!

STEP 2

1. Factor out the common term
2. Factor the quadratic
3. Solve for yy

STEP 3

Alright, let's **kick things off** by noticing that each term in our equation has a yy!
That means we can **factor it out**!
Think of it like reverse distribution.
We're pulling out the common factor to simplify things.
This gives us: y(y28y9)=0y \cdot (y^2 - 8y - 9) = 0 Why did we do this?
Because now we have a much simpler equation to work with!

STEP 4

Now, we're left with a **quadratic expression** inside the parentheses: y28y9y^2 - 8y - 9.
Let's **factor this bad boy**!
We're looking for two numbers that multiply to 9-9 and add up to 8-8.
Think, think, think... How about 9-9 and +1+1?
Yep, those work!
So, we can rewrite the quadratic as: (y9)(y+1)(y - 9) \cdot (y + 1) So, our original equation becomes: y(y9)(y+1)=0y \cdot (y - 9) \cdot (y + 1) = 0 Boom! **Fully factored**!

STEP 5

Now, here comes the **grand finale**!
We have three factors multiplied together that equal zero.
This means at least one of the factors *must* be zero.
So, we set each factor equal to zero and **solve for** yy: y=0y = 0 y9=0    y=9y - 9 = 0 \implies y = 9y+1=0    y=1y + 1 = 0 \implies y = -1

STEP 6

So, the **solutions** to our equation are y=0y = 0, y=9y = 9, and y=1y = -1.
We write this as: y=1,0,9y = -1, 0, 9

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