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 Bihar Board 12th Maths Objective Important Questions Part 1

Bihar Board 12th Maths Objective Important Questions Part 1

Question 1.
Law ab + = b + a is called.
(a) closure law
(b) Associative law
(c) commutative law
(d) distributive law
Answer:
(c) commutative law

Question 2.
Principal value of sin-112√ =
(a) π4
(b) 3π4
(c) 5π4
(d) None of these
Answer:
(a) π4

Question 3.
If y = e3logex then find dydx is equal to:
(a) 3x2
(b) 2log x
(c) 3yx
(d) 3xy
Answer:
(a) 3s2

Question 4.
sin-1x + cos-1x =
(a) π4
(b) π
(c) 0
(d) π4
Answer:
(d) π4

Question 5
If A is skew symmetric matrix of oder 2 then det (A) is of the form :
(a) a2
(b) a2 – 1
(c) a2 + 1
(d) None of these
Answer:
(a) a2

Question 6.
If A = [314−2] then, |A| =
(a) 0
(b) 10
(c) -10
(d) -2
Answer:
(c) -10

Question 7.
If A = ⎡⎣⎢100010001⎤⎦⎥ then A2 =

Answer:
(d)

Question 8.
∣∣∣∣400030002∣∣∣∣ =
(a) 0
(b) 12
(c) 24
(d) 9
Answer:
(c) 24

Question 9.
∣∣∣∣xx2−xyy2−yzz2−z∣∣∣∣=
(a) x3 + y3 + z3
(b) x2 + y2 + z2
(c) x + y + z
(d) 0
Answer:
(d) 0

Question 10.
ddx(sin3x)=
(a) sin3x
(b) 3sin2x cos x
(c) sin 2x
(d) cos2 x
Answer:
(b) 3sin2x cos x

Question 11.
ddx =
(a) 2e2x
(b) e2x
(c) e3x3
(d) 3e3x
Answer:
(a) 2e2x

Question 12.
ddx (5 – cos x) =
(a) 5+sinx
(b) sinx
(c) 5 – sin x
(d) cosx
Answer:
(b) sinx

Question 13.
ddx (sin(logx)] =
(a) 1x cos (logx)
(b) cosx(logx)
(c) xcosx (logx)
(d) sin(logx)
Answer:
(a) 1x cos (logx)

Question 14.
ddx [sec2x – tan2 x] =
(a) 1
(b) 0
(c) 2sec2x
(d) 2tan2x
Answer:
(b) 0

Question 15.
ddx (l2 + m2 + n2) =
(a) 0
(b) 1
(c) 2
(d) 3
Answer:
(a) 0

Question 16.
ddx(tanx−−−−√)=



Answer:
(c)

Question 17.
5i→×2j→=
(a) 10 i⃗ 
(b) 10 j⃗ 
(c) 10 k⃗ 
(d) 0
Answer:
(c) 10 k⃗ 

Question 18.
ddx(i⃗ ×i⃗ )=
(a) 0
(b) 1
(c) 2i⃗ 
(d) 2j⃗ 
Answer:
(a) 0

Question 19.
∫baekxdx=

Answer:
(c)

Question 20.
∫tan2
(a) tan3xe+k
(b) 2tan xsec2x + k
(c) tan x – x + k
(d) 3tan3x + k
Answer:
(c) tan x – x + k

Question 21.
sin-145 + sin-1513 =
If A be a matrix then, (A’)’ equals .
(a) sin-1 6365
(b) sin-1 1665
(e) sin-1 365
(d) 0
Answer:
(a) sin-1 6365

Question 22.
sin-1 35 – sin-11665
(a) cos-11213
(b) cos-1513
(c) cos-112
(d) 0
Answer:
(a) cos-11213

Question 23.
A = [34−2−2] ⇒ A2 =

Answer:
(c)

Question 24.
If A be a matrix then, (A’)’ equals
(a) A’
(b) A
(c) A-1
(d) none of these
Answer:
(b) A

Question 25.
If A and B are matrices, compatible for addition then, (A + B)’ equal
(a) A + B
(b) A’ + B
(c) A + B’
(d) A’ + B’
Answer:
(d) A’ + B’

Question 26.
If A and B art- matrices compatible for multiplication then (AB)’ is equal to
(a) A’B’
(b) A’B
(c) B’A
(d) B’A’
Answer:
(d) B’A’

Question 27.
If A be a singular matrix then |Aj-=
(a) 1
(b) -1
(c) 0
(d) none of these
Answer:
(c) 0

Question 28.
For a symmetric matrix A, |A| is equal to
(a) 0
(b) 1
(c) 2A
(d) none of these
Answer:
(c) 2A

Question 29.
For a skew symmetric matrix A, A + A’ is equal to
(a) 0
(b) 1
(c) 2A
(d) none of these
Answer:
(d) none of these

Question 30.
tan-1 x + tan-1 y is equal to

Answer:
(c)

Question 31.
sin-1 + cos-1x =
(a) 0
(b) 1
(c) π2
(d) π
Answer:
(c) π2

Question 32.
sec-1 + cosec-1x =
(a) 0
(b) 1
(c) π2
(d) π
Answer:
(c) π2

Question 33.
tan-1 + cot-1x =
(a) 0
(b) 1
(c) 2π
(d) π2
Answer:
(d) π2

Question 34.
2tan-1x =

Answer:
(b)

Question 35.
ddx (sin x) =
(a) cos x
(b) sin x
(c) tan x
(d) -cos x
Answer:
(a) cos x

Question 36.
ddx(tanx) = dx
(a) sec x
(b) sec x cot x
(c) sec2x
(d) cot x
Answer:
(c) sec2x

Question 37.
ddx(sin2x) =
(a) sin3x
(b) cos2x
(c) sin2x
(d) -cox2x
Answer:
(c) sin2x

Question 38.
d2dx2(x2) =
(a) 2x
(b) x33
(c) 2
(d) 1
Answer:
(c) 2

Question 39.
d3dx3(x2) =
(a) x33
(b) 2x
(c) 2
(d) 0
Answer:
(d) 0

Question 40.
ddx (cotx) =
(a) cosec2x
(b) -cosec2x
(c) cot x cosec x
(d) cot x
Answer:
(b) -cosec2x

Question 41.
यदि  r⃗ =xi⃗ +yj⃗ +zk⃗  तो r⃗ =xi⃗ +yj⃗ +zk⃗  =
(a) x2 + y2 + z2
(b) x2+y2+z2−−−−−−−−−−√
(c) x + y + z
(d) x2+y2+z2z
Answer:
(b) x2+y2+z2−−−−−−−−−−√

Question 42.
a⃗ ⋅b⃗ =
(a) ab cos θ
(c) ab tan θ
(b) ab sin θ
(d) ab sec θ
Ans.
(a) ab cos θ

Question 43.
a⃗ ×b⃗ =
(a) ab cosθ
(b) ab sinθ
(c) absinθn^
(d) abcosθn^
Ans.
(d) abcosθn^

Question 44.
i⃗ ×j⃗ =
(a) 1
(b) 0
(c) j⃗ 
(d) k⃗ 
Answer:
(d) k⃗ 

Question 45.
k⃗ ×k⃗ =
(a) 0
(b) 1
(c) 0→
(d) z→
Answer:

Question 46.
i⃗ ×j⃗ =
(a) k→
(b) 0
(c) 1
(d) z→
Answer:
(b) 0