Many times I see the chord:

 

-----

-----

--7--

-----

--5--

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However, I guess I am not one hundred percent sure how to play it. In rock smith, it only shows the yellow (5) and the orange (7) notes, and I strum the second, third, and forth strings. However Rocksmith doesn't show the third note, the blue one to strum. How do you play that chord? Some say mute the third string. I am not even sure how to do just that.

I just have the finger on the seven fret slightly touching that string and it mutes it when i strum that.  Not sure if thats the real way it should be done but it seems to work for me.

I strum the second, third, and forth strings.

 

Either that's a typo or you have your string order the wrong way around. High E is the 1st string so in your tab you are strumming the 5th, 4th and 3rd string.

 

Assuming you have your 1st finger on the 5th fret of the 5th string and 3rd finger on the 7th fret of the 3rd string. You lean the Ist finger over so it is touching the 4th string. This stops the 4th string from sounding.

 

It's also good practice to mute the 2nd string with your 3rd finger in the same way. That way if you strum too far you are not playing an unwanted note.

That's an octave - it's not really a chord because they're both the same note (D) just an octave apart.

 

I fret the 5 with my index finger, which also lightly touches and mutes the low E string.  The ring finger frets the 7 and mutes the D string.  They both kind of lay across the rest of the strings so they don't ring out.

 

One variation in Rocksmith I've seen is in the opening riff of High and Dry by Radiohead that has octaves with the top strings ringing out. 

 

---0---

---0---

---0---

---13-

-------

---11-

-------

I see that a lot as well.  And I use a frethand mute as people describe here to mute the middle string.  But I never like the way octaves sound.  It could be my guitar but they rarely sound like what the song actually sounds like.

I find the quickest way to strum an octave-shape is to use your index finger (the one holding the fifth fret on A in this case) to mute the adjacent D string by holding it at a pseudo-barre-chord angle, so you fret A on the fifth fret with the tip and mute with the side of the index finger around the knuckle closest to the top.

 

Another way is to hold the 'full' (three-note) power chord shape and slightly depress the ring finger on the D string to make it into a frethand mute, but you run into a risk of accidentally sounding a harmonic in some positions.

 

Basically it's the same thing, but you either use the normal D5 (5-7-7) or the inverted D5 (5-5-7, shows up in, for example, Peace of Mind) shape and mute the middle string.