Question bank on Definite & Indefinite Integration There are 168 questions in this question bank. Select the correct alternative : (Only one is correct) Q.1 1/def The value of the definite integral, (ex1 e3x )1 dx is 1 1 tan1 1 (A*) 4e2 dx (B) 4e ex dx (C) e2 2 (D) 2e2 [Hint: I = (e·ex e3 ·ex ) = e(e2x e2 ) (multiply Nr and Dr by ex) put ex = t ex dx = dt I = dt 2 2 = 1 tan1 t = 1 = Ans. ] e e t e e2 e e e2 2 4 4e2 Q.2 The value of the definite integral, cos ex2 ·2x ex2 dx is 2/def 0 (A) 1 (B) 1 + (sin 1) (C*) 1 – (sin 1) (D) (sin 1) – 1 2 [Hint: put ex2 = t; ex2 · 2x dx = dt ; cost dt 1 = sin t 2 = 1 – (sin 1) ] 1 2 Q.35/def Value of the definite integral ( sin1(3x 4x3) cos1(4x3 3x) ) dx 1 2 (A) 0 (B*) 2 (C) 7 2 (D) 2 [Hint: Note that in 1 , 1 , sin–1(3x – 4x3) = 3 sin-1x and cos–1(4x3 – 3x) = 2 – 3 cos–1x 2 2 hence f (x) = 3 sin–1x – 2 + 3 cos–1x = 2 1/ 2 I = dx ] 1/ 2 [Alternate: f (x) = sin–1 (3x – 4x3) – [ – cos–1(3x – 4x3 ) ] = – + (sin–1 (3x – 4x3) + cos–1 (3x – 4x3)) = ] 2 x dt Q.46/def Let f (x) = 2 and g be the inverse of f. Then the value of g'(0) is (A) 1 (B) 17 (C*) (D) none of these [Sol. f ' (x) = dy = dx dx now g ' (x) = dy = x 1 x4 dt when y = 0 i.e. 2 hence g '(0) = = 0 then x = 2 (think !) = ] Q.56/inde cot1(ex ) ex 1 dx is equal to : cot1(ex ) 1 cot1(ex ) (A) 2 ln (e2x + 1) e + x + c (B) 2 ln (e2x + 1) + e + x + c 1 (C*) 2 cot1(ex ) ln (e2x + 1) e x + c (D) 1 2 cot1(ex ) ln (e2x + 1) + e x + c 1 k 1 Q.69/def Lim k0 (1 sin 2x) x dx k 0 (A) 2 (B) 1 (C*) e2 (D) non existent k 1 (1 sin 2x) x dx [Hint: l = Lim 0 k0 k differentiating 1 Lim 1 (sin 2k) Using L'opital rule l = Lim (1 sin 2k) k k 0 = ek0 k = e2 ] ln 5 ex ex 1 Q.711/def 0 ex 3 dx = (A*) 4 (B) 6 (C) 5 (D) None [Hint : put ex 1 = t2 ] 1 dt 2 3 t2 sin 2t Q.816/def If x satisfies the equation 2 0 t x 2t cos 1 – 3 t2 1 dt x – 2 = 0 (0 < < ), then the value x is (A) ± (B) ± (C) ± (D*) ± 2 3 t2 sin 2t [Sol. 3 t2 1 dt = 0 as the integrand is an odd function. 1 dt 1 t cos 1 also 0 2 2t cos 1 = sin tan 1 = sin 0 2sin Thus the given equation reduces to x2 2sin – 2 = 0 x = ± 2 Ans.] x Q.917/def If f (x) = eg(x) and g(x) = 2 t d t 1 t 4 then f (2) has the value equal to : (A*) 2/17 (B) 0 (C) 1 (D) cannot be determined [Hint : f (x) = eg (x). g (x) ; g