In theory it is impossible for a scale to have but a flat and a sharp but if it is in inharmonics then yes it is possible to have a flat and a sharp just depends on how you look at it.
The dominant (fifth) degree of a D sharp major scale is A sharp.
D flat, E flat, F flat, G Flat, A flat, B Double flat, C flat, D flat. However, since D flat and C sharp are, essentially, the same, it would be easier to write in terms of C sharp. The scale would then read C sharp, D sharp, E, F sharp, G sharp, A, B, C sharp.
there is no F# scale on Eb saxaphone....
There is no difference in terms of each scale would sound, as F-sharp and G-flat are the same exact note. However, when notated on sheet music, they would look different, as the F-sharp scale would use only sharps, and the G-flat scale would use only flats.
UP: d sharp e sharp f sharp g sharp a sharp b sharp c double-sharp d sharp DOWN: d sharp c sharp b natural a sharp g sharp f sharp e sharp d sharp
The dominant (fifth) degree of a D sharp major scale is A sharp.
C, C sharp/D flat, D, D sharp/E flat, E, F, F sharp/G flat, G, G sharp/A flat, A, A sharp/B flat, B, C.
No. There are a (plus a flat and a sharp), b (plus b flat and b sharp), c (flat and sharp), d (flat and sharp), e (flat and sharp), f (flat and sharp), and g (flat and sharp). That makes a, b, c, d, e, f, g Plus the flat and sharp for each, making 21 notes of the scale.
A minor
D flat, E flat, F flat, G Flat, A flat, B Double flat, C flat, D flat. However, since D flat and C sharp are, essentially, the same, it would be easier to write in terms of C sharp. The scale would then read C sharp, D sharp, E, F sharp, G sharp, A, B, C sharp.
there is no F# scale on Eb saxaphone....
it has a C sharp but no D natural
D minor - more specifically, D harmonic minor (the version of the minor scale with a flat 6 and a sharp 7). However, you will never see a key signature with a B flat and a C sharp. The key signature will only contain B flat.
There is no difference in terms of each scale would sound, as F-sharp and G-flat are the same exact note. However, when notated on sheet music, they would look different, as the F-sharp scale would use only sharps, and the G-flat scale would use only flats.
UP: d sharp e sharp f sharp g sharp a sharp b sharp c double-sharp d sharp DOWN: d sharp c sharp b natural a sharp g sharp f sharp e sharp d sharp
There are different rules. For major keys, the rule is this (by the way, # means sharp): C major scale- 0 sharps or flats G major scale- 1 sharp - F sharp D major scale- 2 sharps - F and C sharp A major scale- 3 sharps - F, C, G sharp E major scale- 4 sharps - F, C, G, D sharp B major scale- 5 sharps - F, C, G, D, A sharp F# major scale- 6 sharps - F, C, G, D, A, E sharp C# major scale - 7 sharps - F, C, G, D, A, E, B sharp. For major keys with flats: F major scale - 1 flat - B flat B flat major scale - 2 flats - B, E flat E flat major scale - 3 flats - B, E, A flat A flat major scale - 4 flats - B, E, A, D flat D flat major scale - 5 flats - B, E, A, D, G flat G flat major scale - 6 flats - B, E, A, D, G, C flat C flat major scale - 7 flats - B, E, A, D, G, C, F flat So as you might have noticed, in increasing order of sharps it is: F, C, G, D, A, E, B. And the increasing order of flats is B, E, A, D, G, C, F. If you notice the order of sharps is the opposite of the order of flats.
The half steps in an E major scale are from Gis / G-sharp (enharmonically, As / A-flat) to A, and from Dis / D-sharp (enharmonically, Es / E-flat) to E.