Algebra · real student question

Find the root of the equation 8/(x + 6) = -5.

Question

Find the root of

8x+6=5\frac{8}{x+6} = -5

Step-by-step solution

  1. Record the excluded value first. The denominator vanishes at x=6x = -6, so whatever root appears, it must not equal 6-6. Noting this before clearing the fraction is what makes the final check meaningful.

  2. Multiply both sides by (x + 6).

    8=5(x+6)8 = -5(x+6)

    This is legitimate exactly because x6x \ne -6 makes the multiplier non-zero.

  3. Expand and collect.

    8=5x305x=38x=385=7.68 = -5x - 30 \quad\Longrightarrow\quad 5x = -38 \quad\Longrightarrow\quad x = -\frac{38}{5} = -7.6

  4. Check the root against the exclusion. 7.66-7.6 \ne -6, so the root is admissible.

  5. Verify in the original equation. x+6=7.6+6=1.6x + 6 = -7.6 + 6 = -1.6, and 81.6=5\tfrac{8}{-1.6} = -5. The sign works out because a positive numerator over a negative denominator is negative, as the right-hand side demands.

Answer

x=385=7.6x = -\frac{38}{5} = -7.6

Need to solve a different problem like this? Open the solver →