I want to play a dominant 9th chord as in the first diagram shown here. There’s no way I can get my second finger to bend onto the fifth (A) string while my third finger is holding down the 1st, 2nd and 3rd strings. How is this possible?
Difficult to say without watching you. Experiment with different guitar positions, try raising or lowering the neck, try resting the guitar on either leg if you are sitting and try different wrist angles in both axis.
There’s many things that might be making it more difficult for you but often it’s one or some of the above reasons. Your finger is never going to bend any more than it does now so it’s a matter of finding a different angle to make it work.
The 2nd finger might need to go further towards the 6th string to give the 5th string some clearance. I’ve just looked at my hand with this chord and the 2nd finger is pushing on the sixth string but just pressing lightly so it’s damped. I’m pretty sure perseverance and practice will sort it out eventually.
If you just can’t get it then you could try playing the chord without the 1st string (fifth of the chord) so it’s a neutral note and often left out of chords with no noticeable effect, especially if it’s just being strummed.
E: x –
B: 3 – 4th finger (pinky)
G: 3 – 3rd finger (ring)
D: 2 – 1st finger (index)
A: 3 – 2nd finger (middle)
E: x