Question bank / Linear equations in one variable

Math · AlgebraMedium

Which of the following equations has no solution?

A

3(x−2)=3x−63(x - 2) = 3x - 6

B

3(x−2)=2x−63(x - 2) = 2x - 6

C

3(x−2)=3x+63(x - 2) = 3x + 6

D

3(x−2)=−3x+63(x - 2) = -3x + 6

Show answer and explanation

Answer: C

The left side of each equation is 3x−63x - 6. An equation of the form 3x−6=ax+b3x - 6 = ax + b has no solution when the coefficients of xx match but the constants don't. In choice C, 3x−6=3x+63x - 6 = 3x + 6 leads to −6=6-6 = 6, which is never true, so the equation has no solution.

Choice A has the same coefficient of xx on both sides, but its constants also match, so it has infinitely many solutions, not none.

Why the other choices are wrong

  • A. Both sides equal 3x - 6, so every value of x is a solution. This equation has infinitely many solutions.
  • B. Subtracting 2x - 6 from both sides gives x = 0, so this equation has exactly one solution.
  • D. The x-coefficients are 3 and -3, so the x-terms don't cancel. Solving 6x = 12 gives the single solution x = 2.
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