Five and nine tenths in expanded form and standard

Step-by-step explanation:

The verbiage "five and nine tenths" can refer to the mixed number 5 9/10, or to the decimal in standard form, 5.9. Simply converting the phrase to a decimal gets you the standard form.

The expanded form can be written a number of ways, depending on how you like to show the place value multipliers. The simplest expanded form is simply the sum of the digits:

  5 + 0.9

You can show the multipliers in standard form:

  5×1 + 9×0.1

Or, you can show the multipliers in exponential form:

  5×10⁰ +9×10⁻¹