Question

Difficulty: EasyMultiplying Polynomials

What is the coefficient of the kk term in the expanded product of (3k−2)(3k - 2) and (k+5)(k + 5)?

Answer: 13

Answer

13
When expanding (3k−2)(k+5)(3k - 2)(k + 5), the kk terms are generated by multiplying the outer terms (3k×5=15k)(3k \times 5 = 15k) and the inner terms (−2×k=−2k)(-2 \times k = -2k). Combining these gives 15k−2k=13k15k - 2k = 13k. Therefore, the coefficient of the kk term is 13.

Step-by-Step Solution

1
Identify the terms that will produce a kk term when multiplied.
The outer terms are 3k3k and 55. The inner terms are −2-2 and kk.
Only the product of a variable term and a constant term will result in a term with degree 1 (kk).
2
Multiply the outer terms.
(3k)(5)=15k(3k)(5) = 15k
This is the 'Outer' multiplication step in expanding two binomials.
3
Multiply the inner terms.
(−2)(k)=−2k(-2)(k) = -2k
This is the 'Inner' multiplication step in expanding two binomials.
4
Combine the resulting like terms.
15k+(−2k)=13k15k + (-2k) = 13k
Combining like terms gives the final kk term of the expanded polynomial.
5
Identify the coefficient.
13
The coefficient is the numerical factor of the kk term.

Key Concept

Multiplying polynomials and combining like terms
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