Sunday, 14 August 2022

Revision XII(Maths) 22/23

Tangent and Normal


1) Write down the equation of the tangent at a point (4,3) on the ellipse 9x²+ 16y²= 288.

2) Write down the equation of the tangent of the parabola y²= 4x at (1,2).

3) write down the value of slope of the tangent to the parabola y² = 8(x - 6) at the point (8,-4).

4) Determine the points on the curve y= x+ 1/x, where the tangent is parallel to x-axis.

5) Find the gradient of the tangent to the parabola y² = 4x at the point (1,2).

6) Show that the equation of the normal to the hyperbola x = a sec t, y= b tan t at the point (a sec t, b tan t) is . ax cos t + by cot t= a²+ b².

7) At a point P(x,y) on the parabola y= x²/4 + 1, the tangent makes an angle 45° with the positive direction of the x-axis. Find the coordinates of the point P.

8) Find the condition that the straight line lx + my = n touches the ellipse x²/a² + y²/b² = 1.

9) Write down the equation of the tangent and normal of the parabola y²= 4ax at (0,0).

10) Obtain the equation the normal to the hyperbola x²/a² - y²/b² = 1 at (a sec t, b tan t).

11) If the straight line lx + my = 1 is a normal to the parabola y²= 4ax, then show that al³+ 2alm² = m².

12) Find the coordinates of the point on the curve y= 1+ 2x- 3x² at which the tangent make an angle of 45° with the positive direction of the x-axis.

13) Find the equation of the tangent to the hyperbola x²/a² - y²/b² = 1 at (a sec t, b tan t).

14) find the equations of the tangent and normal to the ellipse 4x² + 9y² = 72 at the point (3,2).

15) Find the equation of the tangent to the parabola y² = 4x + 5, which is parallel to the straight line y= 2x+ 7.

16) Find the equation of the normal to the curve y= x² - x at the point (3,6). Show that this normal touches the parabola x² + 660y = 0.

17) If the straight line lx + my = n is normal to the hyperbola x²/a² - y²/b² = 1, then show that a²/l² - b²/m² = (a² + b²)²/n².

18) If the straight line x cos t+ y sin t= p touches the ellipse x²/a² + y²/b² = 1, then prove that a² cos²t + b² sin²t = p².

19) Prove that the straight line x+ y= 2+ √2 touches the circle x²+ y² - 2x - 2y+ 1= 0. Find the point of contact.

20) If the straight line lx + my + n= 0 touches the parabola y²= 4ax then prove that am² = nl.

21) tangent are drawn from origin to the curve y= sinx. Prove that their points of contact lie on x²y² = x² - y².

22) Find the equation of the tangent and the normal to the curve y= x³ - 3x at the point (2,2).

23) Find the equation of the tangent and normal of the curve y(x - 2)(x -3) - x +7= 0 at the point of intersection with the x-axis.

24) Find the equation of the common tangent to the parabola y² = 4ax and x²= 4by.

25) Show that the normal at any point on the curve x= a(cos t+ t sin t), y= a(sin t - t cos t) is a constant distance from the origin.



Continuity

1) A function f(x) is defined as:
        =   x²        when x< 1
 f(x)=  2.5       when x= 1
       =  x²+2     when x> 1
Is f(x) continuous at x= 1?

2) A function f(x) is defined as:
        = 3+ 2x        when -3/2≤x< 0
 f(x)=  3- 2x       when 0≤ x< 3/2
       =  -3x -2x     when x ≥ 3/2
Show that f(x) continuous at x= 0 and discontinuous at x=3/2.

3) A function f(x) is defined as:
        =(Sin 3x)/2x        when x≠ 0
 f(x)=  2/3       when x= 0
Is f(x) continuous at x= 0 ?

4) Find the points of discontinuity of the function (x²+2x+5)/(x²-7x+12).

5) A function f(x) is defined as:     
 f(x)=(x⁴+4x³+2x)/sin x  when x≠0
       And f(0)=0
Show that f(x) continuous at x= 0

6) A function f(x) is defined as:
 f(x)= x sin(1/x)       when x≠ 0
       =  0                     when x = 0
Show that f(x) continuous at x= 0

7) The function f(x) is defined as:
        =x²-2x+3       when x< 1
 f(x)=  2                 when x= 1
       =2x²-5x+5      when x> 1
Is f(x) continuous at x= 1 ?

8) f(x)= (x²-1)/(x³-1) is undefined at x= 1. What should be the value of f(x) at x= 1 such that f(x) may be continuous at x= 1 ?

9) For what value of f(4), the function f(x) = (x²-16)/(x-4) is continuous at x= 4 ?

10) Examine the continuity of the function f(x) at x= 1.
 f(x)= |x-1|/(x-1)      when x≠1
       =  0                    when x = 1
Is f(x) continuous at x= 1?

11) Test whether the following function is continuous at x= 0 :
 f(x)= |x|/x         when x≠ 0
       =  1             when x = 0

12) A function f(x) is defined as:
        = x+1        when x≤ 1
 f(x)= 3- ax²     when x > 1
Find the value of a for which f(x) will be continuous at x= 1 ?

13) A function f(x) is defined as:
 f(x)=(x³+x²-16x+20)/(x-2)² at x≠2
       =  K                      at x= 2
If f(x) continuous for all values of x then find the value of K.

14) Determine the values of a so that the following function is continuous at x= 1
 f(x)= ax+3,       when x ≥ 1 
       = x²+a²       when x < 1

15) Two function f(x) and g(x) are defined as:
 f(x)= x²+4      when x ≤ 2
       = x+6       when x > 2 
And g(x)= 2x      when x ≤ 2
               = 4        when x > 2
Show that f(x). g(x) is continuous at x = 2.

16) The function f(x)={log(1+ax) - log(1- bx)}/x is not defined at x= 0. Find the value of f(0), so that f(x) is continuous at x= 0.

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Answers



1) no 3) no 4) 4,3 7) yes 8) 2/3 9) 8 
10) continuous at x= 1
11) discontinuous at x= 0  12) 1
13) 7      14) 2, -1  16) a+ b


DIFFERENTIATION

1) logₑ x

2) log₁₀x

3) x ⁻³⁾²

4) x + 1/x

5) x⁴ +6

6) sin 4x

7) sin(x²)

8) ₑ√x

9) log(sin x)

10) cos ⁻¹(ₑ√tanx)

11) a |sinx| + 2x

12) 3x⁵+ 7x⁴ - 2x² - x + 6

13) 1+ x + x²/2! + x³/3! + x⁴/4!

14) √x + 2√x² + 3√x³ + 4√x⁴ + 5√x⁵

15) 5x³/⁵√x² - 3x/³√x⁴ + 7x/⁷√x² + 12 ⁴√/³√x.

16) logₐx + log xᵃ + eˡᵒᵍˣ + logeˣ + e¹⁺ˣ

17) 10ˣ. x¹⁰.

18) (x²+7)(x³+10)

19) √x eˣ

20) x secx log(x eˣ)

21) (1+ sinx)/(1- sinx).

22) 2 cosx/(1- sinx)²

23) (cos x - cos 2x)/(1- cos x).

24) (x³ - 2 + 1/x³)/(x - 2 + 1/x)

25) (eˣ + e³ˣ)/(eˣ + e⁻ˣ)

26) e²ˣ(1+ 2x)

27) √(2x) - √(2/x) + (x+4)/(4 - x)

28) {f(x)}ⁿ

29) √(log x)

30) tan⁵x

31) (tan⁻¹x)²

32) ₑ(ax² + bx +c)

33) ₑ{√(x+1) - ₑ √(x -1)}

34) ₇(x²+ 2x)

35) log(sinx)

36) log(ax²+ bx +c)

37) log(secx + tanx)

38) log ₛᵢₙ ₓ 

39) logₑ{x + √(x²±a²)}

40) sin€(x)

41) cos(ax + b)

42) sinx°

43) sinx sin 2x sin 3x

44) sin⁻¹(x/a)

45) cot⁻¹(cosec x+ cotx)

46) log(cos x²)

47) 2 tan⁻¹√{(x - a)/(b - x)}

48) cot⁻¹{√(1+ x²)}

49) cos⁻¹{(1- x²)/(1+ x²)}

50) sin⁻¹{2x/(1+ x²)}

51) tan⁻¹{2x/(1- x²)}

52) tan⁻¹{1/√(x² - 1)}

53) tan⁻¹{(3x - x³)/(1- 3x²)} at x= 1

54) tan⁻¹{cosx/(1- sinx)}

55) cos(sin⁻¹x) + tan(cot⁻¹x)

56) sin(cos⁻¹x) + 1/2 sin⁻¹{2x/(1+ x²)}

57) f(logx) where f(x)= logx

58) tan⁻¹{cosx/(1+ sinx)} + sin(eˣ)

59) logₓ(tanx)

60) log √{(1- cosx)/(1+ cosx)} + aˣ.

61) sinx/(1+ cosx)

62) tan⁻¹√{(1- x)/(1+x)}

63) cos{2 tan⁻¹(cosx)}

64) x√(x² + a²)+ a² log{x+ √(x²+ a²)} at x= 0

65) eᵅˣ sin bx.

66) log₁₀ √{(1- cosx)/(1+ cosx)}

67) tan⁻¹√{(1+ cos 2x)/(1- cos 2x)}

68) ₑ√cotx.

69) ₃√(1+ x + x²)

70) log sec(ax + b)³

71) log{2x + 4 + √(4x² + 16x - 22)}

72) tan log sin(ₑx²)

73) xˣ

74) ₓ(1+ x + x²).

75) (tanx)ˢᶦⁿ ˣ at x= π/4.

76) x ᶜᵒˢˣ sin(logₑx)

77) sin⁻¹{2x/(1+ x²)} w.r.t. cos⁻¹{(1- x²)/(1+ x²)}.

78) ₓsin⁻¹x w.r.t. sin⁻¹x.

79) (tan⁻¹x)/(1+ tan⁻¹x) w.r.t. tan⁻¹x.

80) cos⁻¹{(1- x²)/(1+ x²)} w.r.t. tan⁻¹{2x/(1- x²)}.

81) cos⁻¹{(1- x²)/(1+ x²)} w.r.t. sin⁻¹{2x/(1+ x²)}.

82) log[eˣ{(x -1)/(x +1)}³⁾²].

83) {x³√(x² - 12)}/³√(20 - 3x) at x= 4.

84) [x/{1+ √(1- x²)}]ⁿ.

85) cos⁻¹{(8x⁴ - 8x²+1)}

86) xʸ = eˣ⁻ ʸ

87) log(x²+ x+1)/(x² - x +1)

88) tan⁻¹{(cosx - sinx)/(cosx + sinx)}

89) sin⁻¹{2ax √((1- a²x²)}.

90) cos⁻¹{(3 + 5 cosx)/(5+ 3 cosx)}

91) log√{(a cosx - b sinx)/(a cosx + b sinx)}.

92) sin{2 tan⁻¹√{(1 - x)/(1+ x)}.

93) tan⁻¹[√{(a - b)/(a+ b)} tan(x/2)]

94) 3x⁴ - x²y + 2y³= 0

95) x³ + y³ = 3axy.

96) eˣʸ - 4xy = 2.

97) ₓcos⁻¹x

98) xy = cos(xy) at x= π/2 ,y= 0.

99) xʸ. yˣ = 1.

100) (x+ 2)/{(x -1)(x +5)}

101) ₓcos²x

102) x= log(xy)

103) xʸ+ yˣ = 1.

104) ₐx²

105) (sinx)ᶜᵒˢ ˣ+ (cosx) ˢᶦⁿ ˣ.

106) log(xy)= eˣ ⁺ʸ + 2

107) (cosx)ʸ = (siny)ˣ.

108) xᵖ yᑫ = (x + y)ᵖ⁺ᑫ

109) ax² + by² + 2hxy + 2gx + 2fy + c= 0.

110) x= at², y= 2at.

111) x= a cos k,.y = b sin k.

112) x= sin²t, y = tan t.

113) x= a(2t + sin 2t), y = a(1- cos 2t).

114) sinx= 2t/(1+ t²), tan y = 2t/(1- t²).

115) tan⁻¹{t/√(1- t²)} and x= sec⁻¹{1/(2t² - 1)}.

116) y= sin⁻¹(3t - 4t³), x= sec⁻¹{1/(1- 2t²)}

117) y= ₑsin⁻¹t, x= ₑ⁻ cos⁻¹t, 

118) y= a sin³t, x= a cos³t.

119) y= a(sint - t cos t), x= a(cost + t sin t) at t= 3π/4.

120) tan y= 2t/(1- t²), cosx = (1- t²)/(1+ t²).

121) x= 3at/(1+ t³), y= 3at²/(1+ t³).

122) [{tanx}ᵗᵃⁿˣ] ᵗᵃⁿ ˣ at x=π/4

Prove:
1) If cos y = x cos(a+ y), then show dy/dx= (cos²(a+ y))/sin a.

2) If sin y = x sin(a+ y), then show dy/dx= (sin²(a+ y))/sin a = sin a/(1- 2x cos a + x²)

3) If √(1- x²) + √(1 - y²) = a(x - y) then show dy/dx= √{(1- y²)/(1- x²)}

4) If f(x)= {(a+ x)/(b+ x)}ᵃ⁺ᵇ⁺ ²ˣ then show f'(0) = {2 log(a/b) + (b² - a²)/ab}{a/b}ᵃ⁺ᵇ.

5) If y= x²/2 + x/2 √(x²+ 1) + log✓√{x + √(x²+1)}] then prove 2y = x dy/dx + log(dy/dx)

6) If x= a sin 2t(1+ cos 2t), y= a cos 2t(1- cos 2t), then show 1+ (dy/dx)² = sec²t



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