Given: (3+2)x+(3−2)x=10
Now, let (3+2)x=t⇒(3−2)x=t1
So, (3+2)x+(3−2)x=10
⇒t+t1=10
⇒t2−10t+1=0
⇒t=5±26
⇒t=(3−2)2,(3+2)2
Now, taking (3+2)x=(3−2)2=(3+2)−2 we get, x=−2
And equating (3+2)x=(3+2)2 we get, x=2
Hence, the number of elements in S is 2