Algebra · real student question

Solve the equation 5x - 4 = 2x + 11.

Question

Solve

5x4=2x+115x-4=2x+11

Step-by-step solution

  1. Move the smaller variable term across. Subtract 2x2x from both sides:

    5x2x4=113x4=115x-2x-4=11\quad\Longrightarrow\quad 3x-4=11

  2. Move the constant across. Add 44 to both sides:

    3x=11+4=153x=11+4=15

  3. Divide by 33.

    x=153=5x=\frac{15}{3}=5

  4. Check both sides. With x=5x=5:

    left=5(5)4=21,right=2(5)+11=21\text{left}=5(5)-4=21,\qquad\text{right}=2(5)+11=21

    Equal, so x=5x=5 \checkmark. Because the coefficients of xx differ (525\ne 2), the equation was guaranteed to have exactly one solution — equal coefficients would have signalled either no solution or infinitely many.

Answer

x=5x=5

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