(i) Find the domain of the function f(x)=x2+2x+1x2−8x+12.
(ii) Let A={8,11,15,12,15,18,23} and f be function from A→N, such that f(x) is the highest prime factor of x. Find f and its range.
(i) Here, f(x)=x2+2x+1x2−8x+12
Since, f(x) is a rational function of x.
Hence, f(x) assumes real value of x except for those values of x for which x2−8x+12=0.
⇒ x2−8x+12=0 ⇒ (x−6)(x−2)=0 ⇒ x=2 and 6
∴ Domain of function = R−{2,6}
(ii) Given, A={8,11,15,12,18,23} and f is a function from A→N such that
f(x) = Highest prime factor of x
∴ f(8) = Highest prime factor of 8 = 2
f(11) = Highest prime factor of 11 = 11
f(12) = Highest prime factor of 12 = 3
f(15) = Highest prime factor of 15 = 5
f(18) = Highest prime factor of 18 = 3
f(23) = Highest prime factor of 23 = 23
f={(8,2),(11,11),(12,3),(15,5),(18,3),(23,23)}
Hence, range of f is {2,11,3,5,23}