MENU

RD Chapter 4 Algebraic Identities Ex MCQS Solutions

Question - 11 : -
If a – b = -8 and ab = -12 then a3 – b3 =
(a) -244
(b) -240
(c) -224
(d) -260

Answer - 11 : -

a – b = -8, ab = -12
(a – b)3 = a3 – b3 – 3ab (a –b)
(-8)3 = a3 – b3 – 3 x (-12)(-8)
-512 = a3-b3– 288
a3 – b3 = -512 + 288 = -224     (c)

Question - 12 : -
If the volume of a cuboid is 3x2 – 27, then its possible dimensions are
(a) 3, x2, -27x
(b) 3, x – 3, x + 3
(c) 3, x2, 27x
(d) 3, 3, 3

Answer - 12 : -

Volume = 3x2 -27 = 3(x2 – 9)
= 3(x + 3) (x – 3)
∴Dimensions are   = 3, x – 3, x   + 3        (b)

Question - 13 : -
75 x 75 + 2 x 75 x 25    + 25 x 25 is equal to
(a) 10000
(b) 6250
(c) 7500
(d) 3750

Answer - 13 : -


Question - 14 : - (x – y) (x + y)(x2 + y2) (x4 +y4) is equal to
(a) x16 – y16
(b) x8 – y8
(c) x8 + y8
(d) x16 + y16

Answer - 14 : -


Question - 15 : -

Answer - 15 : -


Question - 16 : -

Answer - 16 : -


Question - 17 : -

Answer - 17 : -


Question - 18 : -

Answer - 18 : -


Question - 19 : -
If a2 + b2 + c2 – ab – bc – ca = 0, then
(a) a + b = c
(b) b + c = a
(c) c + a = b
(d) a = b = c

Answer - 19 : -

a2 + b2 + c2 –ab – bc – ca = 0
2 {a2 + b2 + c2 – ab – be – ca)= 0 (Multiplying by 2)
⇒ 2a2 + 2b2 + 2c2– 2ab – 2bc – 2ca = 0
⇒ a2 + b2 – 2ab + b2 + c2 –2bc + c2 + a2 – 2ca = 0
⇒ (a – b)2 + (b – c)2 + (c – a)2 =0
(a – b)2 = 0, then a – b = 0
⇒ a = b
Similarly, (b – c)2 = 0, then
b-c = 0
⇒ b = c
and (c – a)2 = 0, then c-a = 0
⇒ c = a
∴ a = b– c           (d)

Question - 20 : -

Answer - 20 : -


Free - Previous Years Question Papers
Any questions? Ask us!
NodeJS Interview Questions Answers
ASP.Net Interview Questions Answers
Interview Questions Answers
×