{"id":3840,"date":"2021-08-09T09:30:20","date_gmt":"2021-08-09T09:30:20","guid":{"rendered":"https:\/\/mathemerize.com\/?p=3840"},"modified":"2021-11-21T01:07:41","modified_gmt":"2021-11-20T19:37:41","slug":"continuity-of-a-function","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/continuity-of-a-function\/","title":{"rendered":"Definition of Continuity of a Function"},"content":{"rendered":"
This tutorial is for you if you are searching for – “Definition of Continuity of a function, Discontinuity and Missing Point Discontinuity.”<\/p>\n
Let’s begin –<\/p>\n
A Function for which a small change in the independent variable causes only a small change and not a sudden jump in the dependent variable are called continuous functions. Naively, we may say that a function is continuous at a fixed point if we can draw the graph of the function around that point without lifting the pen from the plane of the paper.<\/p>\n
A function f(x) is said to be continuous at x = a, if<\/p>\n
\n\\(\\displaystyle{\\lim_{x \\to a}}\\) f(x) = f(a). <\/strong><\/p>\n<\/blockquote>\n
Symbolically f is continuous at x = a if<\/p>\n
\n\\(\\displaystyle{\\lim_{h \\to 0}}\\) f(a – h) = \\(\\displaystyle{\\lim_{h \\to 0}}\\) f(a + h) = f(a), h > 0 <\/strong><\/p>\n
i.e. \\(LHL_{x = a}\\) = \\(RHL_{x = a}\\) equals value of ‘f’ at x = a.<\/strong><\/p>\n<\/blockquote>\n\n\n
Example : <\/span> If f(x) = {\\(sin{\\pi x\\over 2}\\), x < 1 and [x], x \\(\\geq\\) 1} then find whether f(x) is continuous or not at x = 1, where [ ] denotes greatest integer function.<\/p>\n\t
Solution : <\/span>For continuity at x = 1, we determine, f(1), \\(\\displaystyle{\\lim_{x \\to {1^-}}}\\) f(x) and \\(\\displaystyle{\\lim_{x \\to {1^+}}}\\) f(x)
Now, f(1) = [1] = 1
\\(\\displaystyle{\\lim_{x \\to {1^-}}}\\) f(x) = \\(\\displaystyle{\\lim_{x \\to {1^-}}}\\) \\(sin{\\pi x\\over 2}\\) = \\(sin{\\pi\\over 2}\\) = 1 and \\(\\displaystyle{\\lim_{x \\to {1^+}}}\\) f(x) = \\(\\displaystyle{\\lim_{x \\to {1^+}}}\\) [x] = 1
so f(1) = \\(\\displaystyle{\\lim_{x \\to {1^-}}}\\) f(x) = \\(\\displaystyle{\\lim_{x \\to {1^+}}}\\) f(x)
\\(\\therefore\\) f(x) is continuous at x = 1.
<\/p>\n\n\nContinuity of a function in an interval<\/h2>\n
(a) A function is said to be continuous in (a,b) if f is continuous at each & every point belonging to (a, b).<\/p>\n
(b) A function is said to be continuous in a closed interval [a,b] if :<\/p>\n
\n(i) f is continuous in the open interval (a,b)<\/p>\n
(ii) f is right continuous at ‘a’ i.e. \\(\\displaystyle{\\lim_{x \\to {a^+}}}\\) f(x) = f(a) = a finite quantity.<\/p>\n
(iii) f is left continuous at ‘b’ i.e. \\(\\displaystyle{\\lim_{x \\to {b^-}}}\\) f(x) = f(b) = a finite quantity.<\/p>\n<\/blockquote>\n
Note :<\/strong><\/p>\n
(i) All polynomials, trigonometrical functions, exponential & logarithmic functions are continuous in their domains.<\/p>\n
(ii) If f(x) & g(x) are two functions that are continuous at x = c then the function defined by:<\/p>\n
\\(F_1(x)\\) = f(x) + g(x); \\(F_2(x)\\) = Kf(x), where K is any real number; \\(F_3(x)\\) = f(x).g(x) are also continuous at x = c.<\/p>\n
Further, if g(c) is not zero, then \\(F_4(x)\\) = \\(f(x)\\over g(x)\\) is also continuous at x = c.<\/p>\n
Hope, you learnt definition of continuity of a function and continuity of a function at a point and over an interval. Practice more question on continuity of a function to learn more and get ahead in competition. Good Luck!<\/p>\n\n\n