lcm and hcf Model Questions & Answers, Practice Test for ibps rrb po officer scale 1 prelims 2024

Answer: (c)

Here, $a^3 b – ab^3 = ab (a^2 – b^2)$ = ab(a – b)(a + b)

$a^3b^2 + a^2b^3 = a^2b^2$(a + b) and

ab (a + b) = ab (a + b)

∴ LCM [($a^3 b – ab^3), (a^3b^2 + a^2b^3$), ab (a + b)]

= $a^2b^2 (a + b) (a – b) = a^2b^2 (a^2 – b^2)$

Answer: (c)

Answer: (e)

Suppose first number is x and second number is y.

y = 0.3x = $4/5$y

y – 0.8 y = 0.3x

0.2 y = 0.3 x

$x/y=2/3$

Answer: (c)

For integers a, b and c, if HCF (a, b) = 1 and HCF (a, c) = 1, then HCF (a, bc) = 1

Answer: (c)

Pure recurring decimal:-

A decimal fraction in which all the figures occur repeatedly is called a pure recurring decimal as 7.4444 .., 2.666 ...., etc.

Let P be prime number

So P = 7, 11, 13,...

$1/7$ = .142857142857 ....

$1/{11}$ = .09090909 ....

$1/{13}$ = 0.0769230769230...

All above example are pure recurring decimal and its period will (p –1)