Warm-up

Some equations involving powers or indices can be solved “by inspection” if we are familiar with the powers of common numbers. Try these

  1. \(2^x = 16\)

  2. \(10^x = 0.001\)

  3. \(5^x = 125\)

  4. \(\big(\frac{1}{3}\big)^x = 81\)

  1. \(x = 4\) because \(16 = 2^4\)

  2. \(x = -3\) because \(0.001 = \frac{1}{1000} = \frac{1}{10^3}\)

  3. \(x = 3\)

  4. \(x = -4\) because \(\big(\frac{1}{3}\big)^{-1} = 3\)

Some other equations look very similar but are not so easy to solve. Think about this one \[10^x = 562\] What could you do to find an approximate answer? How accurate could you make your estimate?

What are \(10^2\) and \(10^3\)? Can you state upper and lower bounds for the value of \(x\)?

How can you narrow down the range of possible values?