Question

Difficulty: EasyEvaluating Algebraic Expressions

If x=−3x = -3 and y=−4y = -4, what does the expression 5x−2y5x - 2y equal?

  1. -7Answer
  2. B
    -23
  3. C
    23
  4. D
    7

Answer

-7
Substituting the given values into the expression yields 5(−3)−2(−4)5(-3) - 2(-4). Multiplying the terms results in −15−(−8)-15 - (-8), which simplifies to −15+8-15 + 8. Adding these numbers correctly produces −7-7.

Step-by-Step Solution

1
Substitute x=−3x = -3 and y=−4y = -4 into the algebraic expression.
5(−3)−2(−4)5(-3) - 2(-4)
Variable substitution replaces each variable with its given numerical value using parentheses.
2
Multiply the terms according to the order of operations.
−15−(−8)-15 - (-8)
Multiplication is performed before subtraction: 5×−3=−155 \times -3 = -15 and 2×−4=−82 \times -4 = -8.
3
Simplify the double negative and add the integers.
−15+8=−7-15 + 8 = -7
Subtracting a negative number is equivalent to adding its positive counterpart.

Key Concept

Evaluating Algebraic Expressions
Estimated Time:45s
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