Let a, b ∈ R be such that the function f given by f(x) = ln |x

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 Multiple Choice QuestionsMultiple Choice Questions

1.

On the ellipse 4x2 + 9y2 = 1, the points at which the tangents are parallel to the line 8x = 9y, are

  • 25, 15

  • - 25, 15

  • - 25, - 15

  • 25, - 15


2.

A container s the shape of an inverted cone. Its height is 6 m and radius is 4m at the top. If it is filled with water at the rate of 3m/min then the rate of change of height of water(in mt/min) when the water level is 3 m is

  • 34π

  • 29π

  • 16π

  • 2π


3.

 If α, β, γ are the lengths of the tangents from the vertices of a triangle to its incircle. Then

  • α + β + γ = 1r2αβγ

  • α + β + γ = 1rαβγ

  • 1α + 1β + 1γ = rαβγ

  • α2 + β2 + γ2 = 2rαβγ


4.

If a cylindrical vessel of given volume V with no lid on the top is to be made from a sheet of metal, then the radius (r) and height(h) of the vessel so that the metal sheet used is minimum is

  • r = πV3, h =  πV3

  • r = πV, h = πV

  • r = Vπ3, h = Vπ3

  • r = Vπ, h = Vπ


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5.

A wire of length 2 units is cut into two parts which are bent respectively to form a square of side=x units and a circle of radius=r units. If the sum of the areas of the square and the circle so formed is minimum, then:

  • 2x=(π+4)r

  • (4−π)x=πr

  • x=2r

  • x=2r

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6.

Let f (x) be a polynomial of degree four having extreme values at x =1 an x =2. If limit as straight x rightwards arrow 0 of open square brackets 1 plus fraction numerator straight f left parenthesis straight x right parenthesis over denominator straight x squared end fraction close square brackets space equals space 3 comma then f(2) is equal to 

  • -8

  • -4

  • 0

  • 0

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7.

A spherical balloon is filled with 4500π cubic meters of helium gas. If a leak in the balloon causes the gas to escape at the rate of 72π cubic meters per minute, then the rate (in meters per minute) at which the radius of the balloon decreases 49 minutes after the leakage began is

  • 9/7

  • 7/9

  • 2/9

  • 2/9

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8.

Let a, b ∈ R be such that the function f given by f(x) = ln |x| + bx
2+ ax, x ≠ 0 has extreme values at x = –1 and x = 2.
Statement 1: f has local maximum at x = –1 and at x = 2.
Statement 2: straight a space equals space 1 half space and space straight b space equals space fraction numerator negative 1 over denominator 4 end fraction

  • Statement 1 is false, statement 2 is true

  • Statement 1 is true, statement 2 is true; statement 2 is a correct explanation for statement 1

  • Statement 1 is true, statement 2 is true; statement 2 is not a correct explanation for statement 1

  • Statement 1 is true, statement 2 is true; statement 2 is not a correct explanation for statement 1


B.

Statement 1 is true, statement 2 is true; statement 2 is a correct explanation for statement 1

(i) A function f, such that f(x)= log |x| +bx2 +ax, x≠0
(ii) The function 'f' has extrema at x = -1 and x =2 i.e, f'(1) = f'(2) = 0 and f''(-1) ≠ 0≠f''(2)
Now, given function f is given by 
f(x) = log |x| +bx2 +ax
rightwards double arrow space straight f apostrophe left parenthesis straight x right parenthesis space equals space 1 over straight x space plus 2 bx space plus straight a
rightwards double arrow space straight f apostrophe apostrophe space left parenthesis straight x right parenthesis space equals space fraction numerator negative 1 over denominator straight x squared end fraction space plus 2 straight b
Since 'f' has extrema at x = - 1 and x =2
Hence, f'(-1) = 0 =f'(2)
f'(-1) = 0 
⇒ a-2b =1 ..... (i)
and f'(2) = 0 
⇒ a+ 4b = -1/2
solving eq. (i) and (ii), we get
a =1/2 and b = -1/4
straight f apostrophe apostrophe space left parenthesis straight x right parenthesis space equals space fraction numerator negative 1 over denominator straight x squared end fraction space plus fraction numerator negative 1 over denominator 2 end fraction space equals space minus space open parentheses fraction numerator straight x squared space plus 2 over denominator 2 straight x squared end fraction close parentheses
⇒ f'' has local maxima at both x = - 1 and x =2
Thus, a statement I is correct. Also, while solving for the statement I, we found values of a and b, which justify that statement 2 is also correct.

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9.

If dy/dx = y + 3 > 0 and y(0) = 2, then y(ln2) is equal to:

  • 7

  • 5

  • 13

  • 13

158 Views

10.

Equation of the ellipse whose axes are the axes of coordinates and which passes through the point (-3, 1) and has eccentricity square root of 2 over 5 end root is

  • 3x2 + 5y2 -32 = 0

  • 5x2 + 3y2 - 48 = 0

  • 3x2 + 5y2 - 15 = 0 

  • 3x2 + 5y2 - 15 = 0 

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