Given S=\left\{x \in Z: x²-7 x+6 \leq 0
and x^2-3 x>0\right\} ...(i) Now
x2−7x+6≤0 and and x2−3x>0⇒(x−6)(x−1)≤0 and ⇒(x−0)(x−3)>0⇒x∈[1,6] and ⇒x∈(−∞,0)∪(3,∞)Hence equation (i) can be reduced to
and S={x∈Z:x∈[1,6]∩((−∞,0)∪(3,∞)) and ⇒S={x∈Z:x∈(3,6]} and ⇒S={4,5,6}Hence number of elements in set '
S ' are ' 3 '