Important points chap 1 book 2

Range of constant function is singleton set.

The graph of identity function is a straight line which passes through origin and 

bisects 1^st and 4^th quadrant.

(0, ∞)= +ve real numbers

[0, ∞ )=non –ve real numbers

(-∞,0)= -ve numbers

(-∞, 0]=non +ve numbers

Symmetry of a curve:

Replace y by –y. if unchanged then it is symmetric about x-axis.

Replace x by –x. if unchanged then it is symmetric about y-axis.

Replace x by –x and y by –y . if unchanged then it is symmetric about origin.