Practice Questions
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Q77.Let y(x) be the solution of the differential equation 2x2 dy + (ey β2x)dx = 0, x > 0. If y(e) = 1, then y(1) is equal to: (1) loge(2e) (2) loge 2 (3) 2 (4) 0
Q78.Let βa,βb and βcbe three vectors such that βa =βb Γ (β β Γβc). β Ο 2 respectively and the angle between b and βcis ΞΈ(0 < ΞΈ < 2 ), then the value of 1 + tan ΞΈ is equal to : (1) β3 + 1 (2) 2 (3) 1 (4) β3+1 β3 JEE Main 2021 (27 Jul Shift 2) JEE Main Previous Year Paper
Q78.The vector equation of the plane passing through the intersection of the planes βrβ (Λi +Λj + Λk) = β2, and the point (1, 0, 2) is: βrβ (Λi β2Λj) = 73 (1) βrβ (Λi + 7Λj + 3Λk) = 7 (2) βrβ (Λi β7Λj + 3Λk) = 7 = 37 (4) βrβ (3Λi + 7Λj + 3Λk) (3) βrβ (Λi + 7Λj + 3Λk)
Q78.The equation of the line through the point (0, 1, 2) and perpendicular to the line xβ12 = y+13 = zβ1β2 is : yβ1 (1) x 3 = β4 = zβ23 (2) x3 = yβ14 = zβ23 (3) β3x = yβ14 = zβ23 (4) x3 = yβ14 = zβ2β3
Q78.A plane passes through the points A(1, 2, 3), B(2, 3, 1) and C(2, 4, 2). If O is the origin and P is (2, β1, 1) ββ , then the projection of OP on this plane is of length: (1) β25 (2) β27 (3) β23 (4) β211
Q78.Let βπ, βπ, βπ be three vectors mutually perpendicular to each other and have same magnitude. If a vector βπ satisfies βπΓ {βπ- βπΓ βπ} + βπΓ {βπ- βπΓ βπ} + βπΓ {βπ- βπΓ βπ} = β0, then βπ is equal to: (1) 1 (βπ+ βπ+ βπ) (2) 1 (2βπ+ βπ- βπ) 3 3 (3) 1 (βπ+ βπ+ βπ) (4) 1 ( βπ+ βπ+ 2 βπ) 2 2
Q78.The distance of the point 1, 1, 9 from the point of intersection of the line = = and the plane 1 2 2 π₯+ π¦+ π§= 17 is: (1) 19β2 (2) 2β19 (3) β38 (4) 38
Q78.The lines x = ay β1 = z β2 and x = 3y β2 = bz β2, (ab β 0) are coplanar, if: (1) b = 1, a βR β{0} (2) a = 1, b βR β{0} (3) a = 2, b = 2 (4) a = 2, b = 3
Q78.Let y = y(x) be the solution of the differential equation exβ1 βy2 dx + ( xy )dy = 0, y(1) = β1 Then the value of (y(3))2 is equal to: (1) 1 β4e3 (2) 1 β4e6 (3) 1 + 4e3 (4) 1 + 4e6 β
Q78.Let βa = Λi + Λj + 2Λk and b = βΛi + 2Λj + 3Λk. Then the vector product Γ Γ is equal to : (βa+βb) ((βa ((βaββb) Γβb)) Γβb) + + (1) 5(34Λi β5Λj 3Λk) (2) 7(34Λi β5Λj 3Λk) + + (3) 7(30Λi β5Λj 7Λk) (4) 5(30Λi β5Λj 7Λk)
Q78.A hall has a square floor of dimension 10 m Γ 10 m (see the figure) and vertical walls. If the angle GPH between the diagonals AG and BH is cosβ1 15 , then the height of the hall (in meters) is: (1) 5β2 (2) 5β3 (3) 5β10 (4) 5
Q78.Let the vectors 2 + π+ π ^π+ π+ 2π+ π ^π- π+ π ^π, 1 + π ^π+ 2π ^π- π ^π and 2 + π ^π+ 2π ^π+ 1 - π ^π, βπ, π, πβπ be co-planar. Then which of the following is true? (1) 2π= π+ π (2) 3π= π+ π (3) π= π+ 2π (4) 2π= π+ π
Q78.Let βa = 2Λi β3Λj + 4Λk and b = 7Λi + Λj β6Λk If βrΓβa =βrΓ b,βrβ (Λi Λk) equal to: (1) 12 (2) 8 (3) 13 (4) 10
Q78.Let L be the line of intersection of planes βrβ (Λi βΛj + 2Λk) = 2 and βrβ (2Λi + Λj βΛk) foot of perpendicular on L from the point (1, 2, 0), then the value of 35(Ξ± + Ξ² + Ξ³) is equal to: (1) 101 (2) 119 (3) 143 (4) 134
Q78.Let the position vectors of two points P and Q be 3Λi βΛj + 2Λk and Λi + 2Λj β4Λk, respectively. Let R and S be two points such that the direction ratios of lines PR and QS are (4, β1, 2) and (β2, 1, β2), respectively. Let ββββ β β lines PR and QS intersect at T . If the vector TA is perpendicular to both PR and QS and the length of vector ββ TA is β5 units, then the modulus of a position vector of A is : (1) β482 (2) β171 (3) β5 (4) β227 P divides the line
Q78.In a triangle ABC , if BCβ = 8, CAβ = 7, ABβ = 10 , then the projection of the vector ABβ on ACβ is equal to : (1) 25 (2) 85 4 14 (3) 127 (4) 115 20 16 β β β
Q78.Let a, b and c be distinct positive numbers. If the vectors aΛi + aΛj + cΛk,Λi + Λk and cΛi + cΛj + bΛk are co-planar, then c is equal to: 2 (1) (2) a+b 1 2 1 + a b (3) a 1 + 1b (4) βab
Q78.The equation of the plane passing through the line of intersection of the planes βrβ (Λi + Λj + Λk) + 4 = 0 and parallel to the x-axis, is βrβ (2Λi + 3Λj βΛk) + + 6 = 0 (1) βrβ (Λi 3Λk) + 6 = 0 (2) βrβ (Λi β3Λk) + 6 = 0 (3) βrβ (Λj β3Λk) β6 = 0 (4) βrβ (Λj β3Λk)
Q78.Let O be the origin. Let OPβ = xΛi + yΛj βΛk and OQβ = βΛi + 2Λj + 3xΛk, x, y βR, x > 0, be such that ββββββ β β β β PQ = β20 and the vector OP is perpendicular to OQ. If OR = 3Λi + zΛj β7Λk, z βR, is coplanar with OP ββ and OQ, then the value of x2 + y2 + z2 is equal to (1) 7 (2) 9 (3) 2 (4) 1
Q78.The distance of the point (1, β2, 3) from the plane x βy + z = 5 measured parallel to a line, whose direction ratios are 2, 3, β6 , is (1) 2 (2) 5 (3) 3 (4) 1 units from the origin, which contains the line of intersection of the
Q78.The integral β« (2xβ1) cos β(2xβ1)2+5 dx is equal to (where c is a constant of integration) β4x2β4x+6 (1) 2 1 sin β(2x β1)2 + 5 + c (2) 21 cos β(2x + 1)2 + 5 + c (3) 1 2 cos β(2x β1)2 + 5 + c (4) 12 sin β(2x + 1)2 + 5 + c
Q78.The distance of line 3π¦- 2π§- 1 = 0 = 3π₯- π§+ 4 from the point ( 2, - 1, 6 ) is : (1) 2β5 (2) 2β6 (3) β26 (4) 4β2
Q78.If (x, y, z) be an arbitrary point lying on a plane P which passes through the point (42, 0, 0), (0, 42, 0) and (0, 0, 42), then the value of expression 3 + xβ11 + yβ19 + zβ12 β 14(xβ11)(yβ19)(zβ12)x+y+z is (yβ19)2(zβ12)2 (xβ11)2(zβ12)2 (xβ11)2(yβ19)2 (1) 0 (2) 3 (3) 39 (4) β45
Q78.Let L be a line obtained from the intersection of two planes x + 2y + z = 6 and y + 2z = 4 . If point P(Ξ±, Ξ², Ξ³) is the foot of perpendicular from (3, 2, 1) on L, then the value of 21(Ξ± + Ξ² + Ξ³) equals: (1) 102 (2) 142 (3) 68 (4) 136
Q78.Let βa = Λi + Λj + Λk andβb = Λj βΛk. If βcis a vector such that βaΓβc=βb and βaβ βc= 3, then βaβ (β Γβc) to: (1) 6 (2) β2 (3) 2 (4) β6