Let f(x) = ∫ex (x-1)(x-2)dx. Then f decreases in the interval (1) (-∞, -2) (2) (- 2, - 1) (3) (1, 2) (4) (2, ∞) Solution: Given f(x) = ∫ex (x-1)(x-2)dx Differentiate both sides w.r.t.x... View Article
If for f(x) = 2x – x2, Legranges’s theorem satisfies in [0, 1], then the value of c in [0,1] is (1) c = 0 (2) c = ½ (3) c = ¼ (4) c = 1 Solution: According to Legranges’s theorem f’(c) = [f(b) - f(a)]/(b - a) Given f(x) = 2x... View Article
The function (e2x – 1)/(e2x + 1) is (1) Increasing (2) Decreasing (3) Even (4) Strictly increasing Solution: Let f(x) = (e2x - 1)/(e2x + 1) = (e2x + 1 - 2)/(e2x +... View Article
If f(x) = x5 – 20x3 + 240x, then f(x) satisfies which of the following (1) It is monotonically decreasing everywhere (2) It is monotonically decreasing only in (0, ∞) (3) It is monotonically increasing everywhere... View Article
The line 2x + √6y = 2 is a tangent to the curve x2 – 2y2 = 4. The point of contact is (1) (4, -√6) (2) (7, -2√6) (3) (2, 3) (4) (√6, 1) Solution: Given equation of line 2x + √6y = 2 y = (2 - 2x)/√6 …(i) Equation of... View Article
The triangle formed by the tangent to the curve f(x) = x2 + bx – b at the point (1, 1) and the co-ordinate axes, lies in the first quadrant. If its area is 2 then the value of b is 1) –1 2) 3 3) –3 4) 1 Solution: Given f(x) = x2 + bx - b Slope, m = dy/dx = 2x + b At (1,1) m = 2 + b The equation of the... View Article
The length of sub-tangent to the curve x2y2 = a4 at the point (-a, a) is 1) 3a 2) 2a 3) a 4) 4a Solution: Given x2y2 = a4 y2 = a4/x2 Differentiate w.r.t.x 2y dy/dx = -2a4/x3 dy/dx = -2a4/2yx3 =... View Article
The abscissa of the points of curve y = x(x – 2) (x – 4) : where tangents are parallel to x-axis is obtained as (1) x = 2 ± 2/√3 (2) x = 1 ± 1/√3 (3) x = 2 ± 1/√3 (4) x = ± 1 Solution: Given y = x(x - 2) (x - 4) = x(x2 - 6x + 8) = x3 - 6x2... View Article
For the curve yn = an-1x, the subnormal at any point is constant. The value of n must be 1) 2 2) 3 3) 0 4) 1 Solution: Given yn = an-1x Differentiate w.r.t.x nyn-1dy/dx = an-1 dy/dx = an-1/nyn-1 Length of... View Article
On dropping a stone in stationary water circular ripples are observed. Rate of flow of ripples is 6 cm/sec. When radius of the circle is 10 cm, then fluid rate of increase in its area is 1) 120 sq. cm/sec 2) 12 sq. cm/sec 3) π sq. cm/sec 4) 120 π sq. cm/sec Solution: Given rate of flow of ripples is 6 cm/sec. dr/dt... View Article
The distance travelled by a particle moving in a straight line at time t is s = √(at2 + 2bt + c). Acceleration of the particle is (1) proportional to t (2) proportional to s (3) proportional to s-3 (4) none of these Solution: Given s = √(at2 + 2bt + c)... View Article
A stone, thrown vertically upward from the surface of the moon at a velocity of 24 m/sec reaches a height of s = 24 t – 0.8t2 metre after t second. The acceleration due to gravity in m/sec2 at the surface of the moon is 1) 0.8 2) -1.6 3) 2.4 4) -4.9 Solution: Given s = 24 t - 0.8t2 Velocity is the derivative of distance. ds/dt = 24 - 1.6 t... View Article
If x = et sin t, y = et cos t, t is a parameter, then d2y/dx2 at t = π is equal to (1) 2e-Ï€ (2) -2e-Ï€ (3) 0 (4) none of these Solution: Given x = et sin t y = et cos t dx/dt = et sin t + et cos t = et (sin t +... View Article
If x = a cos θ, y = b sin θ, then d3y/dx3 is equal to (1) -3b/a3 cosec4 θ cot4 θ (2) -3b/a3 cosec4 θ cot3 θ (3) -3b/a3 cosec4 θ cot θ (4) none of these Solution: Given x = a cos θ... View Article
Differential coefficient of sec-1 1/(2x2 – 1) w.r.t. √(1 – x2) at x = 1/2 is (1) 2 (2) 4 (3) 6 (4) 1 Solution: Let u = sec-1 1/(2x2 - 1) = cos-1 (2x2 - 1) Differentiate w.r.t.x du/dx = [-1/√(1 - (2x2 -... View Article
If z = x√y + y/x1/3, then ∂z/∂y = (1) 0 (2) 1 (3) -1 (4) x/2√y + 1/x1/3 Solution: Given z = x√y + y/x1/3 Differentiate partially w.r.t.y ∂z/∂y = x/2√y + 1/x1/3... View Article
If (x+y) sin u = x2y2, then x ∂u/∂x + y ∂u/∂y is equal to (1) sin u (2) cosec u (3) tan u (4) 3 tan u Solution: Given (x+y) sin u = x2y2 sin u = x2y2/(x+y) = x4(y2/x2)/x(1 + (y/x)) =... View Article
If [latex]u=e^{-x^{2}-y^{2}}[/latex], then (1) xux = yuy (2) yux = xuy (3) yux + xuy = 0 (4) x2uy + y2ux = 0 Solution: Given Differentiate partially ux = Multiply by... View Article
If u = tan-1 (x+y), then x ∂u/∂x + y ∂u/∂y = (1) sin 2u (2) ½ sin 2u (3) 2 tan u (4) sec2 u Solution: Given u = tan-1 (x+y) Differentiate u partially w.r.t.x ∂u/∂x = 1/(1 +... View Article
If u = xy2 tan-1(y/x), then xux+ yuy = (1) u (2) 2u (3) 3u (4) u/3 Solution: Given u = xy2 tan-1(y/x) Differentiate u partially w.r.t.x ux = y2 tan-1(y/x) + xy2 [(1/(1... View Article