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Determine the value of the constant k so that the function is continuous at x = 1.
Ideas required to solve the problem:
1. Meaning of continuity of function – If we talk about a general meaning of continuity of a function f(x) , we can say that if we plot the coordinates (x , f(x)) and try to join all those points in the specified region, we can do so without picking our pen i.e you will put your pen/pencil on graph paper and you can draw the curve without any breakage.
Mathematically we define the same thing as given below:
A function f(x) is said to be continuous at x = c where c is x–coordinate of the point at which continuity is to be checked
…… equation 1
where h is a very small positive no (can assume h = 0.00000000001 like this )
It means :–
Limiting value of the left neighbourhood of x = c also called left hand limit LHL must be equal to limiting value of right neighbourhood of x= c called right hand limit RHL and both must be equal to the value of f(x) at x=c i.e. f(c).
Thus, it is the necessary condition for a function to be continuous
So, whenever we check continuity we try to check above equality if it holds true, function is continuous else it is discontinuous.
We need to find the value of k such that f(x) is continuous at x = 1
Since f(x) is continuous at x = 1
∴ (LHL as x tends to 1) = (RHL as x tends to 1) = f(1)
As, f(1) = k [from equation 2]
We can find either LHL or RHL to equate with f(1)
Let’s find RHL,you can find LHL also.
As, f(x) is continuous
∴ RHL = f(1)
∴ k = –1