Math Problem Statement
Find the coefficient of x^7 in the expansion of (2x-3)^7 Pick the correct answer -2187, -128, 2, or 128
Solution
To find the coefficient of in the expansion of , we can use the Binomial Theorem. The Binomial Theorem states:
In this case, , , and .
We want the term where the power of is exactly 7. In the expansion, the general term looks like this:
We need the power of to be 7, which means the exponent of in must be 7. This occurs when , or .
Now, let's calculate the term when :
This simplifies to:
Thus, the coefficient of is .
The correct answer is 128.
Would you like more details on this process, or do you have any questions?
Here are 5 related questions for further exploration:
- How would the coefficient change if the exponent were higher, say ?
- What if the signs inside the binomial were different, such as ?
- How can the Binomial Theorem be applied to expansions with fractional exponents?
- How would you expand without using the Binomial Theorem?
- What is the general form of the Binomial Theorem for negative exponents?
Tip: Always double-check the signs in binomial expansions, especially when terms involve subtraction!
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Math Problem Analysis
Mathematical Concepts
Algebra
Binomial Expansion
Exponents
Formulas
(a + b)^n = Σ (n choose k) * a^(n-k) * b^k
Theorems
Binomial Theorem
Suitable Grade Level
Grades 9-12
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