Algebra · real student question

Solve the equation 14x + 4 - (6x + 2) = 8x + 2.

Question

Solve

14x+4(6x+2)=8x+214x + 4 - (6x + 2) = 8x + 2

Step-by-step solution

  1. Distribute the minus sign across the whole bracket. The subtraction applies to both terms inside, not just the first:

    14x+46x2=8x+214x + 4 - 6x - 2 = 8x + 2

    Writing 6x+2-6x + 2 here is the usual slip, and it would produce a spurious unique solution.

  2. Combine like terms on the left.

    (14x6x)+(42)=8x+2(14x - 6x) + (4 - 2) = 8x + 2

  3. Compare the two sides.

    8x+2=8x+28x + 2 = 8x + 2

    The two sides are literally the same expression.

  4. Interpret the result. Subtracting 8x+28x + 2 from both sides gives 0=00 = 0, a statement true regardless of xx. When the variable cancels and leaves a true statement, the equation is an identity: every real number satisfies it. (If it had left a false statement such as 0=50 = 5, there would be no solutions at all.)

  5. Spot-check two values. At x=0x = 0: left =0+42=2= 0 + 4 - 2 = 2, right =2= 2. At x=7.5x = 7.5: left =105+447=62= 105 + 4 - 47 = 62, right =60+2=62= 60 + 2 = 62. Both hold, as they must for every xx.

Answer

xR(infinitely many solutions; the equation is an identity)x \in \mathbb{R} \quad \text{(infinitely many solutions; the equation is an identity)}

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