Starting equation: |
( | 19 |
) | x + 1 | = 81 |

Re-write | 19 |
as 3^{-2}, and |

The above two revisions result in this equation

(3^{- 2})^{x+1} = 3^{4}

or

3^{- 2x - 2} = 3^{4}

If the powers are equal, and the bases (here, 3) are equal

then the exponents must also be equal**:**

- 2x - 2 = 4

- 2x = 6

x = -3 |

See Rules for exponents? |