Advertisements
Advertisements
प्रश्न
Discuss the continuity of the following function at the point(s) or on the interval indicated against them:
f(x) = `(cos4x - cos9x)/(1 - cosx)`, for x ≠ 0
f(0) = `68/15`, at x = 0 on `- pi/2 ≤ x ≤ pi/2`
Advertisements
उत्तर
The domain of f(x) is `[- pi/2, pi/2]`
i. For `[- pi/2, pi/2] - {0}`
f(x) = `(cos4x - cos9x)/(1 - cosx)`
It is a rational function and is continuous everwhere except at points where its denominator becomes zero.
Denominator becomes zero when cos x = 1
i.e. x = 0
But x = 0 does not lie in the interval
∴ f(x) is continuous at all points in `[- pi/2, pi/2] - {0}`
ii. For continuity at x = 0
f(0) = `68/15`
`lim_(x -> 0) "f"(x) = lim_(x -> 0) (cos4x - cos9x)/(1 - cosx)`
= `lim_(x -> 0) (2sin ((4x + 9x)/2) * sin((9x - 4x)/2))/(2sin^2 x/2)`
= `lim_(x -> 0) (sin((13x)/2)* sin((5x)/(2)))/(sin x/2)^2`
= `lim_(x -> 0) [((sin((13x)/2) * sin ((5x)/2))/(x^2))/((sin x/2)^2/(x^2))] ...[("Divide numerator and denominator by" x^2),("As" x -> 0"," x ≠ 0 therefore x^2 ≠0)]`
= `(lim_(x -> 0) sin((13x)/2)/x * (sin ((5x)/2))/x)/(lim_(x -> 0) ((sin x/2)/x)^2`
= `(lim_(x -> 0) sin((13x)/2)/((13x)/2) xx 13/2 * lim_(x -> 0) sin ((5x)/2)/((5x)/2) xx 5/2)/(lim_(x -> 0) ((sin x/2)/(x/2))^2 xx 1/4`
= `(1 xx 13/2 xx 1 xx 5/2)/((1)^2 xx 1/4) ...[(because x -> 0"," (13x)/2 -> 0),((5x)/2 -> 0 "and" lim_(theta -> 0) sintheta/theta = 1)]`
= 65
∴ `lim_(x -> 0) "f"(x) ≠ "f"(0)`
∴ f(x) is discontinuous at x = 0
APPEARS IN
संबंधित प्रश्न
Examine the continuity of f(x) = x3 + 2x2 − x − 2 at x = − 2
Examine whether the function is continuous at the points indicated against them :
f(x) `{:( = (x^2 + 18x - 19)/(x - 1)",", "for" x ≠ 1),(= 20",", "for" x = 1):}}` at x = 1
Examine whether the function is continuous at the points indicated against them :
f(x) `{:(= x/(tan3x) + 2",", "for" x < 0),(= 7/3",", "for" x ≥ 0):}} "at" x = 0`
Find all the point of discontinuities of f(x) = [x] on the interval (− 3, 2).
Test the continuity of the following function at the point or interval indicated against them :
f(x) `{:(= ((27 - 2x)^(1/3) - 3)/(9 - 3(243 + 5x)^(1/5))",", "for" x ≠ 0),(= 2",", "for" x = 0):}}` at x = 0.
Identify discontinuities for the following function as either a jump or a removable discontinuity :
f(x) `{:(= 4 + sin x",", "for" x < pi),(= 3 - cos x",", "for" x > pi):}`
Show that following function have continuous extension to the point where f(x) is not defined. Also find the extension :
f(x) = `(x^2 - 1)/(x^3 + 1)` for x ≠ – 1
Discuss the continuity of the following function at the point indicated against them :
f(x) `{:(=("e"^(1/x) - 1)/("e"^(1/x) + 1)",", "for" x ≠ 0),(= 1",", "for" x = 0):}}` at x = 0
If f(x) `{:(= (24^x - 8^x - 3^x + 1)/(12^x - 4^x - 3^x + 1)",", "for" x ≠ 0), (= "k"",", "for" x = 0):}}` is continuous at x = 0, find k
For what values of a and b is the function
f(x) `{:(= (x^2 - 4)/(x - 2)",", "for" x < 2),(= "a"x^2 - "b"x + 3",", "for" 2 ≤ x < 3),(= 2x - "a" + "b"",", "for" x ≥ 3):}}` continuous for every x on R?
Suppose f(x) `{:(= "p"x + 3",", "for" "a" ≤ x ≤ "b"),(= 5x^2 − "q"",", "for" "b" < x ≤ "c"):}`
Find the condition on p, q, so that f(x) is continuous on [a, c], by filling in the blanks.
f(b) = ______
`lim_(x -> "b"^+) "f"(x)` = _______
∴ pb + 3 = _______ − q
∴ p = `"_____"/"b"` is the required condition
Select the correct answer from the given alternatives:
f(x) = `(x^2 - 7x + 10)/(x^2 + 2x - 8)`, for x ∈ [– 6, – 3]
Discuss the continuity of the following function at the point(s) or on the interval indicated against them:
f(x) `{:(= 2x^2 - 2x + 5",", "for" 0 ≤ x ≤ 2),(= (1 - 3x - x^2)/(1 - x) "," , "for" 2 < x < 4),(= (x^2 - 25)/(x - 5)",", "for" 4 ≤ x ≤ 7 and x ≠ 5),(= 7",", "for" x = 5):}`
Identify discontinuity for the following function as either a jump or a removable discontinuity on their respective domain:
f(x) `{:(= x^2 + x - 3,"," "for" x ∈ [ -5, -2)),(= x^2 - 5,"," "for" x ∈ (-2, 5]):}`
Find k if following function is continuous at the point indicated against them:
f(x) `{:(= ((5x - 8)/(8 - 3x))^(3/(2x - 4))",", "for" x ≠ 2),(= "k"",", "for" x = 2):}}` at x = 2
Find k if following function is continuous at the point indicated against them:
f(x) `{:(= (45^x - 9^x - 5^x + 1)/(("k"^x - 1)(3^x - 1))",", "for" x ≠ 0),(= 2/3",", "for" x = 0):}}` at x = 0
Find f(a), if f is continuous at x = a where,
f(x) = `(1 + cos(pi x))/(pi(1 - x)^2)`, for x ≠ 1 and at a = 1
Solve using intermediate value theorem:
Show that 5x − 6x = 0 has a root in [1, 2]
If f(x) = `{:{(tan^-1|x|; "when" x ≠ 0), (pi/4; "when" x = 0):}`, then ______
If function `f(x)={((x^2-9)/(x-3), ",when "xne3),(k, ",when "x =3):}` is continuous at x = 3, then the value of k will be ______.
If the function f(x) defined by
f(x) = `{{:(x sin 1/x",", "for" x = 0),(k",", "for" x = 0):}`
is continuous at x = 0, then k is equal to ______.
For what value of k, the function defined by
f(x) = `{{:((log(1 + 2x)sin^0)/x^2",", "for" x ≠ 0),(k",", "for" x = 0):}`
is continuous at x = 0 ?
Which of the following is not continuous for all x?
If f(x) = `{{:((x - 4)/(|x - 4|) + a",", "for" x < 4),(a + b",", "for" x = 4 "is continuous at" x = 4","),((x - 4)/(|x - 4|) + b",", "for" x > 4):}`
then ______.
If f(x) = `{{:((3 sin πx)/(5x),",", x ≠ 0),(2k,",", x = 0):}`
is continuous at x = 0, then the value of k is ______.
If f(x) = `{{:((sin^3(sqrt(3)).log(1 + 3x))/((tan^-1 sqrt(x))^2(e^(5sqrt(3)) - 1)x)",", x ≠ 0),( a",", x = 0):}`
is continuous in [0, 1] then a is equal to ______.
Which is a necessary condition for continuity at \[x=c\]?
If \[f\] is defined on the closed interval \[[a,b]\], which condition establishes continuity at the left endpoint \[a\]?
When is \[f(x)\] non-removable discontinuous at \[x=a\]?
For \[f(x)=\begin{cases}1,&x\leq0\\2,&x>0\end{cases}\], why is \[f\] discontinuous at \[x=0\]?
At which points is the reciprocal function \[f(x)=\frac{1}{x}\] continuous?
What does the greatest integer function \[f(x)=[x]\] give?
For \[f(x)=|x|=\begin{cases}-x,&x<0\\x,&x\geq0\end{cases}\], what are the LHL, RHL, and \[f(0)\] at \[x=0\]?
For \[f(x)=\begin{cases}x^3+3,&x\ne0\\1,&x=0\end{cases}\], which statement is correct at \[x=0\]?
