You don't need to know many guitar scales to play guitar ... You should be able to see that the C major pentatonic scale uses all the notes from a C chord, plus a couple of extras.

Example 4. The Chinese Scale – Key of C (C-E-F#-G-B) Bars 1-4 Here’s our first major idea, with chords constructed from the C ...

Harmonic minor keys are used when writing chords ... the triads in C major are as follows: Triads can be indicated by Roman numerals of the degrees of the scale. In the jazz styles of Gershwin ...