# What two keys are associated with a fix dominant 7th chord?

The following exercise has me bewildered:

As you can see I instinctively flatted the E and made the key the dominant 7th chord of Bb major. What other key could the author be looking for? Unfortunately there are no examples to go by.

Alternatively, I could have sharped the F, A, and C to make it the dominant 7th chord of B major. But neither of these options can simultaneously describe a dominant 7th chord in two keys, correct?

The chord as I've modified it also is the dominant 7th chord of Bb minor; is that what I'm supposed to put as the second key?

I apologize if this question is not concrete enough, but I'm hoping someone with more experience will see through this mystery.

• I cannot see the image; are you able to re-upload it? But based on your question, a single dominant 7th chord will be the dominant in the major and minor form of a given key; I don't see how it can be a dominant in two keys with two different tonics. Dec 5, 2017 at 2:59
• I deleted and re-uploaded the image. Hopefully it's now visible. But either way I believe you have understood my question perfectly already so it probably will not be helpful.
– user45413
Dec 5, 2017 at 3:04

The exercise means well, but the directions are a bit poor; they could have worded their intentions better to make it more clear.

A single dominant 7th chord will be the dominant in the major and minor form of a given key (e.g., C major and C minor). Although all major-minor 7th chords can appear in any key, each is only the true dominant 7th (in other words, V7) of that single major/minor pair.

As such, your opening F7 will be in the key of B-flat major and B-flat minor. (Or, if you write F-sharp 7, it's B major and B minor.)

• I actually just took a look at the previous page's exercises, which I did last night. On that page, they take turn getting you to identify the major and minor key (using key signatures). With that context, it actually makes sense to give both keys since I am asked to use accidentals here. Anyways it still left me feeling a bit uncertain, so thanks very much for confirming.
– user45413
Dec 5, 2017 at 3:16
• Picture of previous page: i.imgur.com/8PWWxJd.jpg
– user45413
Dec 5, 2017 at 3:17
• Ah, that's fair. Then the directions aren't so bad. (PS: check your last two on question #1 of that previous page, and make sure D is in the bass!) Dec 5, 2017 at 3:19
• Thanks for pointing those mistakes out! :) I've fixed them now; but I could definitely use more practice at that particular exercise. I should just sit down and do it with every note at some point.
– user45413
Dec 5, 2017 at 3:24