Factor Polynomial: Find The Value Of C

by Andrew McMorgan 39 views

Hey mathletes! Ever get stuck trying to figure out a missing piece in a polynomial puzzle? Today, we're diving deep into a super common problem: finding the value of 'cc' when we know a specific factor. Specifically, we're tackling the polynomial p(x)=x3โˆ’4x2+cx+33p(x) = x^3 - 4x^2 + cx + 33 and we're told that (x+3)(x+3) is one of its factors. This is where the Factor Theorem comes to the rescue, guys! It's like a secret handshake in the polynomial world that makes these problems a breeze once you know the trick. So, grab your calculators, your pencils, and let's unravel this mystery together and find that elusive 'cc'. We'll break down exactly why the Factor Theorem works and then apply it step-by-step to our problem, making sure you guys understand every single bit of it. No more head-scratching, just clear, concise math that even your math-averse cousin could follow! We'll explore what it means for something to be a 'factor' of a polynomial, why this relationship allows us to use a specific value, and how that value connects back to the polynomial itself. By the end of this, you'll be a pro at spotting these kinds of problems and solving them with confidence. This isn't just about solving one problem; it's about understanding a fundamental concept that unlocks a whole world of polynomial manipulation. So, let's get started on this mathematical adventure and discover the power of the Factor Theorem!

Understanding the Factor Theorem: The Secret Sauce

Alright, let's get down to brass tacks with the Factor Theorem. What exactly is it, and why is it so darn useful? In simple terms, the Factor Theorem is a direct consequence of the Remainder Theorem. The Remainder Theorem tells us that if you divide a polynomial p(x)p(x) by a linear factor (xโˆ’a)(x-a), the remainder will be p(a)p(a). Pretty neat, right? Now, the Factor Theorem takes this a step further. It states that (xโˆ’a)(x-a) is a factor of a polynomial p(x)p(x) if and only if p(a)=0p(a) = 0. Think about it: if (xโˆ’a)(x-a) is a factor, it means that when you divide p(x)p(x) by (xโˆ’a)(x-a), there's no remainder. And according to the Remainder Theorem, the remainder is p(a)p(a). So, if the remainder is zero, then p(a)p(a) must be zero. Conversely, if p(a)=0p(a) = 0, it means the remainder when dividing by (xโˆ’a)(x-a) is zero, which means (xโˆ’a)(x-a) must be a factor. It's a beautiful, elegant connection that simplifies a lot of polynomial problems. For our specific problem, we're given that (x+3)(x+3) is a factor of p(x)=x3โˆ’4x2+cx+33p(x) = x^3 - 4x^2 + cx + 33. Using the Factor Theorem, we can rewrite (x+3)(x+3) in the form (xโˆ’a)(x-a). Here, aa would be โˆ’3-3. So, if (x+3)(x+3) is a factor, then according to the theorem, p(โˆ’3)p(-3) must equal 0. This is the golden ticket, guys! It transforms our problem from trying to 'find a factor' to simply 'evaluating the polynomial at a specific point and setting it to zero'. This is a huge simplification and is the core idea behind solving these kinds of polynomial factor problems. So, remember this: if (xโˆ’a)(x-a) is a factor, p(a)=0p(a)=0. If p(a)=0p(a)=0, (xโˆ’a)(x-a) is a factor. Itโ€™s a two-way street, and itโ€™s going to be our best friend today. We are not just memorizing a rule; we are understanding the underlying logic that makes it work, which is crucial for tackling more complex math challenges down the line. This theorem is a cornerstone of algebra, and mastering it will serve you well in all your future mathematical endeavors. Itโ€™s a concept thatโ€™s as powerful as it is simple, and once it clicks, youโ€™ll wonder how you ever managed polynomial problems without it. So, let's lock this theorem into our brains and get ready to apply it!

Applying the Factor Theorem: Solving for 'c'

Now that we've got the Factor Theorem firmly in our grasp, let's put it into action to solve for 'cc' in our polynomial p(x)=x3โˆ’4x2+cx+33p(x) = x^3 - 4x^2 + cx + 33. We know that (x+3)(x+3) is a factor. As we established, this means that when we plug x=โˆ’3x = -3 into the polynomial, the result must be zero. So, we need to calculate p(โˆ’3)p(-3) and set it equal to 0. Let's do this step-by-step:

  1. Identify the value of 'x': Since (x+3)(x+3) is the factor, we set it equal to zero to find the root: x+3=0x+3 = 0. Solving for xx, we get x=โˆ’3x = -3. This is the value we need to substitute into our polynomial.
  2. Substitute 'x' into the polynomial: Now, we replace every instance of 'xx' in p(x)=x3โˆ’4x2+cx+33p(x) = x^3 - 4x^2 + cx + 33 with โˆ’3-3. This gives us: p(โˆ’3)=(โˆ’3)3โˆ’4(โˆ’3)2+c(โˆ’3)+33p(-3) = (-3)^3 - 4(-3)^2 + c(-3) + 33
  3. Evaluate the terms: Let's calculate each part of the expression:
    • (โˆ’3)3=(โˆ’3)imes(โˆ’3)imes(โˆ’3)=9imes(โˆ’3)=โˆ’27(-3)^3 = (-3) imes (-3) imes (-3) = 9 imes (-3) = -27
    • (โˆ’3)2=(โˆ’3)imes(โˆ’3)=9(-3)^2 = (-3) imes (-3) = 9
    • So, โˆ’4(โˆ’3)2=โˆ’4(9)=โˆ’36-4(-3)^2 = -4(9) = -36
    • c(โˆ’3)=โˆ’3cc(-3) = -3c
  4. Set up the equation: Now, substitute these evaluated terms back into the expression for p(โˆ’3)p(-3): p(โˆ’3)=โˆ’27โˆ’36โˆ’3c+33p(-3) = -27 - 36 - 3c + 33
  5. Simplify and solve for 'c': We know from the Factor Theorem that p(โˆ’3)p(-3) must equal 0. So, we set our simplified expression equal to zero and solve for 'cc': โˆ’27โˆ’36โˆ’3c+33=0-27 - 36 - 3c + 33 = 0 Combine the constant terms: โˆ’27โˆ’36=โˆ’63-27 - 36 = -63. Then, โˆ’63+33=โˆ’30-63 + 33 = -30. So the equation becomes: โˆ’30โˆ’3c=0-30 - 3c = 0 Now, isolate the term with 'cc': Add 3030 to both sides of the equation: โˆ’3c=30-3c = 30 Finally, divide both sides by โˆ’3-3 to find the value of 'cc': c = rac{30}{-3} c=โˆ’10c = -10

And there you have it, guys! The value of 'cc' that makes (x+3)(x+3) a factor of the polynomial p(x)=x3โˆ’4x2+cx+33p(x) = x^3 - 4x^2 + cx + 33 is -10. Pretty straightforward once you know the Factor Theorem, right? Itโ€™s amazing how one simple theorem can turn a potentially complex algebraic manipulation into a clean substitution and equation-solving problem. This process highlights the elegance of abstract algebra, where seemingly abstract rules have very concrete and practical applications in problem-solving. We went from a polynomial with an unknown coefficient to a specific value by leveraging the fundamental property that a factor corresponds to a root, which in turn means the polynomial evaluates to zero at that root. This methodical approach ensures accuracy and builds a strong foundation for tackling more advanced polynomial concepts, such as polynomial division and finding all roots of a polynomial. Remember this method, because you'll see it pop up again and again!

Verification: Does it Really Work?

So, we found that c=โˆ’10c = -10. But is this correct? A good mathematician always verifies their work! Let's plug c=โˆ’10c = -10 back into our original polynomial to get p(x)=x3โˆ’4x2โˆ’10x+33p(x) = x^3 - 4x^2 - 10x + 33. Now, we need to check if (x+3)(x+3) is indeed a factor. We can do this in a couple of ways. The easiest way, since we just used the Factor Theorem, is to plug x=โˆ’3x = -3 back into this new polynomial and see if we get 0.

Let's calculate p(โˆ’3)p(-3) with c=โˆ’10c=-10: p(โˆ’3)=(โˆ’3)3โˆ’4(โˆ’3)2โˆ’10(โˆ’3)+33p(-3) = (-3)^3 - 4(-3)^2 - 10(-3) + 33 p(โˆ’3)=โˆ’27โˆ’4(9)+30+33p(-3) = -27 - 4(9) + 30 + 33 p(โˆ’3)=โˆ’27โˆ’36+30+33p(-3) = -27 - 36 + 30 + 33 p(โˆ’3)=โˆ’63+63p(-3) = -63 + 63 p(โˆ’3)=0p(-3) = 0

Boom! It equals 0. This confirms that our value of c=โˆ’10c = -10 is correct and that (x+3)(x+3) is indeed a factor of p(x)=x3โˆ’4x2โˆ’10x+33p(x) = x^3 - 4x^2 - 10x + 33.

Another way to verify is by performing polynomial division. If (x+3)(x+3) is a factor, then dividing x3โˆ’4x2โˆ’10x+33x^3 - 4x^2 - 10x + 33 by (x+3)(x+3) should result in a remainder of 0. Let's do a quick synthetic division:

Set up for synthetic division with the root x=โˆ’3x = -3 and coefficients of p(x)p(x): 1, -4, -10, 33.

-3 | 1  -4  -10   33
   |    -3   21  -33
   ------------------
     1  -7   11    0

The last number in the bottom row is the remainder, which is 0. This is fantastic news! It means our division is exact, and (x+3)(x+3) is definitely a factor. The other numbers in the bottom row (1, -7, 11) are the coefficients of the resulting quotient polynomial, which is x2โˆ’7x+11x^2 - 7x + 11. So, we can actually rewrite our original polynomial as: p(x)=(x+3)(x2โˆ’7x+11)p(x) = (x+3)(x^2 - 7x + 11).

This verification process is super important, guys. It not only confirms our answer but also deepens our understanding of the relationship between factors, roots, and the evaluation of polynomials. It shows that the mathematical rules are consistent and reliable. This confidence in our results is what makes learning math so rewarding. Plus, knowing how to verify means you can catch your own mistakes before anyone else does!

Conclusion: Mastering Polynomial Factors

So there you have it, math enthusiasts! We've successfully navigated the world of polynomial factors and found the missing coefficient 'cc' using the powerful Factor Theorem. The key takeaway is that if (xโˆ’a)(x-a) is a factor of a polynomial p(x)p(x), then p(a)p(a) must equal 0. This principle transformed our problem into a straightforward substitution and equation-solving task. We substituted x=โˆ’3x = -3 (derived from the factor x+3x+3) into p(x)=x3โˆ’4x2+cx+33p(x) = x^3 - 4x^2 + cx + 33, set the result to 0, and solved for 'cc', arriving at the value of -10. We then went the extra mile to verify our answer using both the Remainder Theorem (by plugging x=โˆ’3x=-3 back in) and polynomial division (synthetic division), both confirming that our calculated 'cc' value is spot on. This methodical approach โ€“ understand the concept, apply it step-by-step, and verify your results โ€“ is the golden rule for tackling any mathematical problem, especially in algebra. Mastering polynomial factors is a crucial skill that opens doors to understanding more complex mathematical concepts like roots of polynomials, graphing, and even calculus. Keep practicing these types of problems, and you'll find yourself becoming more and more comfortable with algebraic manipulations. Remember, every problem you solve builds your mathematical muscle! Don't be afraid to experiment, make mistakes (because that's how we learn!), and most importantly, have fun with it. The world of mathematics is vast and exciting, and understanding concepts like the Factor Theorem is your key to unlocking its many wonders. So keep that curiosity alive, and happy problem-solving!