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Linear equationsAlgebraMiddle schoolabout 0:49

Solve -x + 1 = 3x + 7: animated lesson

A narrated, step-by-step linear equations video lesson with captions. Final answer: x = -3/2 ≈ -1.5.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.3 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Solving an equation
$- x+1 = 3~ x+7$
2. Step by step
1. $- x+1 = 3~ x+7$
  Start with the equation
2. $-4x + 1 = 7$
  Subtract 3x from both sides
3. $-4x = 6$
  Subtract 1 from both sides
4. $x = \frac{6}{-4} = -\frac{3}{2}$
  Divide both sides by -4
3. The answer
$x = -\frac{3}{2} \approx -1.5$
x = -3/2 ≈ -1.5
4. Check
- x = -1.5: left side = 2.5, right side = 2.5 ✓

Transcript

The problem. Here is the problem: negative x plus 1 equals 3x plus 7. A linear equation in x: isolate x using inverse operations.

Step by step. Start with the equation. Subtract 3x from both sides. Subtract 1 from both sides. Divide both sides by negative 4.

The answer. So the answer is x equals negative 3 over 2 approximately negative 1.5. Doing the same operation to both sides keeps the equation balanced. Undoing addition, then multiplication, leaves x alone.

Check. x equals negative 1.5: left side equals 2.5, right side equals 2.5, which checks out.

About linear equations

Solve one-variable linear equations, including ones with brackets and fractions, and check the solution.

Solve -x + 1 = 3x + 7: Linear equations Step-by-Step Lesson