Solve the linear equation (−1/2) · (x − 5) + 3 = −5/2 and find the exact value of x.

Difficulty: Easy

Correct Answer: 16

Explanation:


Introduction / Context:

This algebra question requires solving a simple linear equation that involves a fractional coefficient and a bracket. It tests your ability to distribute a negative fraction, combine like terms, and isolate the variable x. Such equations appear frequently in aptitude tests and form a foundation for more advanced algebra.



Given Data / Assumptions:

  • The equation is (−1/2) · (x − 5) + 3 = −5/2.
  • x is a real number.
  • Standard arithmetic operations and distribution rules apply.
  • The goal is to find the unique value of x that satisfies the equation.


Concept / Approach:

We first distribute the factor −1/2 across the bracket (x − 5). Then we combine the resulting terms with the constant 3 on the left side. After that, we move constants to one side and keep the x term on the other side. Multiplying by −2 at the right point clears the fraction and makes solving straightforward.



Step-by-Step Solution:

Step 1: Start with the given equation (−1/2)(x − 5) + 3 = −5/2. Step 2: Distribute −1/2 across the bracket: (−1/2) * x = −x/2 and (−1/2) * (−5) = +5/2. Step 3: The equation becomes −x/2 + 5/2 + 3 = −5/2. Step 4: Write 3 as a fraction with denominator 2: 3 = 6/2. Step 5: Combine 5/2 and 6/2: −x/2 + 11/2 = −5/2. Step 6: Move 11/2 to the right side by subtracting it from both sides: −x/2 = −5/2 − 11/2. Step 7: Combine the fractions: −5/2 − 11/2 = −16/2 = −8. Step 8: So −x/2 = −8. Step 9: Multiply both sides by −2 to clear the fraction and the negative sign: x = (−8) * (−2) = 16.


Verification / Alternative check:

Substitute x = 16 back into the original equation. Compute x − 5 = 16 − 5 = 11. Then (−1/2) * 11 = −11/2. Add 3, which is 6/2, to get −11/2 + 6/2 = −5/2, which matches the right side. This confirms that x = 16 satisfies the equation exactly.



Why Other Options Are Wrong:

Substituting 4, −6, −4, or 6 into the equation does not produce −5/2 on the left side. These incorrect values usually result from errors in distributing the minus sign or combining the fractional terms. Only x = 16 gives the required equality.



Common Pitfalls:

Learners often forget that multiplying a negative fraction by a negative number gives a positive term. Others may try to multiply by 2 too early and misplace signs. Carefully distributing and converting integers to fractions with a common denominator greatly reduces the chance of mistakes.



Final Answer:

The solution of the equation (−1/2)(x − 5) + 3 = −5/2 is x = 16.


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