Let f (x) be a polynomial of degree four having extreme values a

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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


C.

0

Any function have extreme values (maximum and minimum) at its critical points, where f'(x)= 0
Since, the function have extreme values at x =1 and x=2
therefore, f'(x) = 0 at x =1 and x= 2
⇒ f'(1) = 0 and f'(2) = 0
Also, it is given that

straight l im with straight x rightwards arrow 0 below space 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
rightwards double arrow 1 plus limit as straight x space rightwards arrow 0 of fraction numerator straight f left parenthesis straight x right parenthesis over denominator straight x squared end fraction space equals space 3
rightwards double arrow space limit as straight x rightwards arrow 0 of space fraction numerator straight f left parenthesis straight x right parenthesis over denominator straight x squared end fraction space equals space 2
⇒ f(x) will be of the form
ax4  + bx3 + 2x4
f(x) is four degree polynomial]
Let f(x) = ax4 +bx3 +2x2
⇒ f'(x) = 4ax3 + 3bx2+ 4x
⇒ f'(1) = 4a +3b+4 = 0
and f'(2)  32a + 12b +8 = 0
⇒ 8a + 3b + 2 = 0
On solving Eqs. (i) and (ii), we get
a = 1/2, b = -2
straight f left parenthesis straight x right parenthesis space space equals space straight x to the power of 4 over 2 space minus space 2 straight x cubed space plus 2 straight x squared
f(2) = 8 - 16 +8 = 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

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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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