Difficulty: Easy
Correct Answer: 2
Explanation:
Introduction / Context:
This is a straightforward linear-equation simplification problem, but it tests a very common trap: subtracting a bracketed expression. When you have (A) - (B), every term inside B changes sign. If you forget to flip the signs, you will get the wrong coefficient of x and the wrong constant. Once simplified correctly, the equation becomes a single-variable linear equation that can be solved in one or two steps.
Given Data / Assumptions:
Concept / Approach:
Distribute the minus sign across the second bracket:
-(4x - 8) = -4x + 8.
Then combine like terms (x terms and constants) and solve the resulting linear equation by isolating x.
Step-by-Step Solution:
1) Start:
(36 - 16x) - (4x - 8) = 4
2) Distribute the minus sign into the second bracket:
36 - 16x - 4x + 8 = 4
3) Combine constants:
36 + 8 = 44
4) Combine x terms:
-16x - 4x = -20x
5) So the equation becomes:
44 - 20x = 4
6) Subtract 44 from both sides:
-20x = 4 - 44 = -40
7) Divide by -20:
x = (-40)/(-20) = 2
Verification / Alternative check:
Substitute x = 2:
LHS = (36 - 16*2) - (4*2 - 8) = (36 - 32) - (8 - 8) = 4 - 0 = 4.
RHS = 4. Both sides match, so x = 2 is correct.
Why Other Options Are Wrong:
• 3, 4, 6, -2: result from sign mistakes when opening the bracket or from incorrect combining of -16x and -4x.
Common Pitfalls:
• Writing -(4x - 8) as -4x - 8 (wrong; the -8 becomes +8).
• Combining constants incorrectly: 36 and 8 must add to 44.
Final Answer:
2
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