Quick questions on Inverting and non-inverting amplifiers explained: O-Level Electronics Amplifiers

In the inverting amplifier, the input signal is applied through an input resistor $R_{in}$ to the inverting input, and the non-inverting input is held at $0\ \text{V}$. The gain is:

In the non-inverting amplifier, the input signal is applied to the non-inverting ($+$) input, and the feedback network ($R_f$ and a resistor $R_{in}$ to $0\ \text{V}$) sets the gain. The gain is:

To design for a particular gain, pick the ratio of the resistors. For an inverting amplifier of gain $-10$, make $R_f$ ten times $R_{in}$ (for example $100\ \text{k}\Omega$ and $10\ \text{k}\Omega$). For a non-inverting amplifier of gain $6$, make $R_f$ five times $R_{in}$, since the formula adds one. The actual values are usually in the kilohm to megohm range.