For what value of the constant c is the function f continuous on (-∞, ∞)? f(x) = {cx2 + 2x/x2 - 1 if x < 2 and x3 - cx if x >= 2
Solution:
Given, the function f(x) = {cx2+ 2x/x2 - 1 if x < 2 and x3 - cx if x >= 2 is continuous on (-∞, ∞).
We have to find the value of the constant c.
We know that f(x) is continuous at x = a if the following conditions are satisfied.
1) f(a) exists.
2) \(\lim_{x \to a}\) f(x) exists and
3) \(\lim_{x \to a}\) f(x) = f(a).
So, we know that for any value of c, for x<2, the function is continuous and for x>=2, the function is continuous.
Therefore, it is the case that we have to check for the continuity of the function at x = 2.
For any value of c, the first two conditions are satisfied.
So, to find c, assume that the third condition is satisfied inorder to make the function continuous.
Now, \(\lim_{x \to 2}\) f(x) = f(2).
\(\lim_{x \to 2}\) f(x) = cx2 + 2x/x2 - 1
f(2) = c(2)2 + 2(2)/(2)2 - 1
f(2) = 4c - 1
\(\lim_{x \to 2}\) f(x) = x3 - cx
f(2) = (2)3 - c(2)
f(2) = 8 - 2c
So, 4c - 1 = 8 - 2c
4c + 2c = 8 + 1
6c = 9
c = 9/6
c = 3/2
c = 1.5
Therefore, the value of c is 1.5
For what value of the constant c is the function f continuous on (-∞, ∞)? f(x) = {cx2 + 2x/x2 - 1 if x < 2 and x3 - cx if x >= 2
Summary:
The function f is continuous on (-∞, ∞), f(x) = {cx2 + 2x/x2 - 1 if x < 2 and x3 - cx if x >= 2, the value of the constant c is 1.5
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