Solve the Fraction Equation: Find X When -7/(x+4) = x-4

Question

Resolve:

7x+4=x4 \frac{-7}{x+4}=x-4

Video Solution

Step-by-Step Solution

To solve this equation, we follow these steps:

  • Step 1: Identify the original equation as 7x+4=x4\frac{-7}{x+4} = x-4.
  • Step 2: Eliminate the fraction by multiplying both sides by x+4x+4:
    7=(x4)(x+4)-7 = (x-4)(x+4).
  • Step 3: Recognize the right-hand side as a difference of squares:
    7=x216-7 = x^2 - 16.
  • Step 4: Rearrange the equation into a standard quadratic form:
    x216+7=0x^2 - 16 + 7 = 0 which simplifies to x29=0x^2 - 9 = 0.
  • Step 5: Factor the quadratic expression:
    (x3)(x+3)=0(x-3)(x+3) = 0.
  • Step 6: Use the zero product property to find potential solutions:
    x3=0x - 3 = 0 which gives x=3x = 3, and
    x+3=0x + 3 = 0 which gives x=3x = -3.
  • Step 7: Validate that neither solution makes the denominator zero, as x4x \neq -4.

Thus, the solutions to the equation 7x+4=x4\frac{-7}{x+4} = x-4 are ±3\pm3.

Answer

±3 \pm3