Math · Elementary Algebra
Solving a Linear Equation
Easy
Math
Elementary Algebra
Question
If 2x + 11 = 17, what is the value of x?
Answer choices
- 2
- 6
- 5
- 4
- 3
E Correct answer: E) 3
Set up the problem carefully before computing. Isolate x by undoing operations in reverse. First subtract the constant, then divide by the coefficient.
Carry the arithmetic through one step at a time, double-checking signs and units. The ACT writes wrong answers to catch the most common slips, so an answer that "looks right" without verification is risky.
Plug the answer back into the original expression as a sanity check whenever the problem allows. If the substitution does not balance, you have made an arithmetic mistake earlier in the work.
The underlying rule
Subtract 11 from both sides: 2x = 6. Divide by 2: x = 6/2 = 3.
Why each wrong answer is wrong
- A) 2: A common arithmetic or sign error leads to this value; carefully redo the calculation.
- B) 6: A common arithmetic or sign error leads to this value; carefully redo the calculation.
- C) 5: A common arithmetic or sign error leads to this value; carefully redo the calculation.
- D) 4: A common arithmetic or sign error leads to this value; carefully redo the calculation.
Study tip
To solve any linear equation, undo operations in reverse order: subtraction/addition first, then multiplication/division.
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