Question

Difficulty: MediumOrder of Operations and Number Properties

For all non-zero real numbers aa, bb, and cc, which of the following is equivalent to the expression a(bc)b(ac)c\frac{a(b - c) - b(a - c)}{c}?

  1. bab - aAnswer
  2. B
    aba - b
  3. C
    a+ba + b
  4. D
    ababab - a - b
  5. E
    2abca+b\frac{2ab}{c} - a + b

Answer

bab - a
Applying the distributive property to the numerator yields abacba+bcab - ac - ba + bc. Since multiplication is commutative, ba=abba = ab, allowing us to cancel the abab and ba-ba terms. This leaves bcacbc - ac in the numerator. Factoring out cc gives c(ba)c(b - a). Dividing the entire numerator by the denominator cc simplifies the expression to bab - a.

Step-by-Step Solution

1
Apply the distributive property to expand the terms in the numerator.
a(bc)b(ac)=abacba+bca(b - c) - b(a - c) = ab - ac - ba + bc
Distribute aa to both bb and c-c, and distribute b-b to both aa and c-c. Remember that multiplying two negative numbers yields a positive result, so b×c=bc-b \times -c = bc.
2
Combine like terms in the expanded numerator.
abacab+bc=bcacab - ac - ab + bc = bc - ac
Since multiplication is commutative, ba=abba = ab. Thus, the terms abab and ab-ab cancel each other out to zero.
3
Factor out the common term cc from the numerator and divide by the denominator cc.
c(ba)c=ba\frac{c(b - a)}{c} = b - a
Factoring out cc from bcacbc - ac gives c(ba)c(b - a). Dividing by cc cancels the common factor in the numerator and denominator, leaving the simplified expression.

Key Concept

Order of Operations and Number Properties
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