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Linear equationsAlgebraMiddle schoolabout 1:01

Solve 4x + 8 = -5x + 7: animated lesson

A narrated, step-by-step linear equations video lesson with captions. Final answer: x = -1/9 ≈ -0.11111111.

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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
$4~ x+8 = -5~ x+7$
2. Step by step
1. $4~ x+8 = -5~ x+7$
  Start with the equation
2. $9x + 8 = 7$
  Add 5x to both sides
3. $9x = -1$
  Subtract 8 from both sides
4. $x = \frac{-1}{9} = -\frac{1}{9}$
  Divide both sides by 9
3. The answer
$x = -\frac{1}{9} \approx -0.11111111$
x = -1/9 ≈ -0.11111111
4. Check
- x = -0.11111111: left side = 7.5555556, right side = 7.5555556 ✓

Transcript

The problem. Here is the problem: 4x plus 8 equals negative 5x plus 7. A linear equation in x: isolate x using inverse operations.

Step by step. Start with the equation. Add 5x to both sides. Subtract 8 from both sides. Divide both sides by 9.

The answer. So the answer is x equals negative 1 over 9 approximately negative 0.11111111. Doing the same operation to both sides keeps the equation balanced. Undoing addition, then multiplication, leaves x alone.

Check. x equals negative 0.11111111: left side equals 7.5555556, right side equals 7.5555556, which checks out.

About linear equations

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

Solve 4x + 8 = -5x + 7: Linear equations Step-by-Step Lesson