To determine the highest degree of the given expression \((3x^2 + 4)(x^5−3)−12x^9−24x^3\), we need to analyze each component.
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Degree of \((3x^2 + 4)(x^5 - 3)\):
- The degree of \(3x^2 + 4\) is 2 (highest power is \(x^2\)).
- The degree of \(x^5 - 3\) is 5 (highest power is \(x^5\)).
- When you multiply two polynomials, the degree of the product is the sum of the degrees of the individual polynomials.
- Therefore, the degree of \((3x^2 + 4)(x^5 - 3)\) is \(2 + 5 = 7\).
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Degree of \(-12x^9\):
- The degree is 9.
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Degree of \(-24x^3\):
- The degree is 3.
Now, we combine the results:
- The degree of \((3x^2 + 4)(x^5 - 3)\) is 7.
- The degree of \(-12x^9\) is 9.
- The degree of \(-24x^3\) is 3.
Next, we find the highest degree among these:
- The degrees we have are 7, 9, and 3.
- The highest degree is \(9\) from the term \(-12x^9\).
Thus, the highest degree of the entire expression \((3x^2 + 4)(x^5 - 3) - 12x^9 - 24x^3\) is \(9\).
The answer is \(C) 9\).