Question

Difficulty: MediumSimplifying Expressions and Combining Like Terms

For all real numbers pp and qq, which of the following is equivalent to the expression 2p2(p−3q)−3q(p2−q2)−(2p3−5p2q)2p^2(p - 3q) - 3q(p^2 - q^2) - (2p^3 - 5p^2q)?

  1. A
    −14p2q+3q3-14p^2q + 3q^3
  2. B
    −4p2q−3q3-4p^2q - 3q^3
  3. −4p2q+3q3-4p^2q + 3q^3Answer
  4. D
    −4p2q+3q2-4p^2q + 3q^2
  5. E
    −14p2q−3q3-14p^2q - 3q^3

Answer

−4p2q+3q3-4p^2q + 3q^3
The correct answer is obtained by distributing all factors and negative signs, then combining the coefficients of the like terms. This yields −4p2q+3q3-4p^2q + 3q^3.

Step-by-Step Solution

1
Distribute the term 2p22p^2 into the first parenthesis, −3q-3q into the second parenthesis, and the negative sign into the third parenthesis.
2p2(p−3q)=2p3−6p2q2p^2(p - 3q) = 2p^3 - 6p^2q
−3q(p2−q2)=−3p2q+3q3-3q(p^2 - q^2) = -3p^2q + 3q^3
−(2p3−5p2q)=−2p3+5p2q-(2p^3 - 5p^2q) = -2p^3 + 5p^2q
Expanding the terms removes the parentheses and prepares the expression for combining like terms.
2
Combine the expanded parts into a single expression and group the like terms together.
(2p3−2p3)+(−6p2q−3p2q+5p2q)+3q3(2p^3 - 2p^3) + (-6p^2q - 3p^2q + 5p^2q) + 3q^3
Grouping terms with identical variable parts makes combining coefficients straightforward.
3
Simplify the coefficients for each group of like terms.
0p3+(−6−3+5)p2q+3q3=−4p2q+3q30p^3 + (-6 - 3 + 5)p^2q + 3q^3 = -4p^2q + 3q^3
Simplifying the combined coefficients yields the final, simplified expression.

Key Concept

Simplifying Expressions and Combining Like Terms
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