Question

Difficulty: HardSimplifying Algebraic Expressions

A mathematical model for a fluid dynamics problem reduces to the following algebraic expression:

−2xy(3x−4y)−[5x2y−2xy(x+3y)] -2xy(3x - 4y) - [5x^2y - 2xy(x + 3y)]

When completely simplified, which of the following represents the equivalent standard form?

  1. A
    −13x2y+2xy2-13x^2y + 2xy^2
  2. B
    −9x2y+2xy2-9x^2y + 2xy^2
  3. −9x2y+14xy2-9x^2y + 14xy^2Answer
  4. D
    5x3y35x^3y^3

Answer

The correct expression is −9x2y+14xy2-9x^2y + 14xy^2.
The correct expression is derived by applying the order of operations and the distributive property. First, evaluate the terms inside the brackets to get 3x2y−6xy23x^2y - 6xy^2. Then expand the initial term to −6x2y+8xy2-6x^2y + 8xy^2. Subtracting the bracket flips the inner signs, yielding −6x2y+8xy2−3x2y+6xy2-6x^2y + 8xy^2 - 3x^2y + 6xy^2. Combining like terms results in −9x2y+14xy2-9x^2y + 14xy^2.

Step-by-Step Solution

1
Expand the inner terms inside the brackets by distributing −2xy-2xy to (x+3y)(x + 3y).
5x2y−2x2y−6xy25x^2y - 2x^2y - 6xy^2
Following the order of operations, simplify grouping symbols first.
2
Combine like terms within the brackets.
3x2y−6xy23x^2y - 6xy^2
To minimize the expression before subtracting it from the leading terms.
3
Distribute −2xy-2xy to the terms in the first parenthesis (3x−4y)(3x - 4y).
−6x2y+8xy2-6x^2y + 8xy^2
To expand the first part of the expression.
4
Subtract the simplified bracketed expression from the expanded first part.
−6x2y+8xy2−(3x2y−6xy2)=−6x2y+8xy2−3x2y+6xy2-6x^2y + 8xy^2 - (3x^2y - 6xy^2) = -6x^2y + 8xy^2 - 3x^2y + 6xy^2
To remove the remaining grouping symbols and properly distribute the negative sign.
5
Combine the remaining like terms to reach the final form.
−9x2y+14xy2-9x^2y + 14xy^2
To express the polynomial in its simplest standard form.

Key Concept

Simplifying complex expressions using the distributive property, managing negative multipliers, and working with nested grouping symbols.
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