4
Q:

A perfect cube is an integer whose cube root is an integer. For example, 27, 64 and 125 are perfect cubes. If p and q are perfect cubes, which of the following will not necessarily be a perfect cube?

 A) 8p B) pq C) pq+27 D) -p

Explanation:

A perfect cube will have prime factors that are in groups of 3; for example 125 has the prime factors 5 x 5 x 5 , and 64 x 125 will also be a cube because its factors will be 4 x 4 x 4 x 5 x 5 x 5

Consider the answer choices in turn.

8 is the cube of 2, and p is a cube, and so the product will also be a cube.

pq will also be a cube as shown above.

pq is a cube and so is 27, but their sum need not be a cube. Consider the case where p =1 and q = 8, the sum of pq and 27 will be 35 which has factors 5 x 7 and is not a cube.

-p will be a cube.

Since the difference between p and q is raised to the power of 6, this expression will be a cube (with cube root = difference squared).

Q:

In math questions answers each questions are solved with explanation. The questions are based from different topics. Care has been taken to solve the questions in such a way that students can understand each and every step

1. Which is greater than 4?

(a) 5,

(b) -5,

(c) -1/2,

(d) -25.

 A) 5 B) 20 C) 2 D) 3

Explanation:

Solution:

5 greater than 4.

1 112
Q:

Which of the following is the largest?

 A) 12/49 B) 7/30 C) 13/56 D) 11/46

Explanation:

In the given options,

12/49 can be written as 1/(49/12) = 1/4.083

7/30 can be written as 1/(30/7) = 1/4.285

13/56 can be written as 1/(56/13) = 1/4.307

11/46 can be written as 1/(46/11) = 1/4.1818

Here in the above,

1/4.083 has the smallest denominator and so 12/49 is the largest number or fraction.

3 339
Q:

7, 16, 36, 78, 144, ?

which number come in place of question mark

 A) 168 B) 196 C) 222 D) 256

Explanation:

16 721
Q:

Which of the following is a rational number?

 A) 0.241 B) 1.732 C) 4 D) All of the above

Explanation:

Any number which can be expressed as a fraction of two integers like P & Q as P/Q where Q is not equal to zero.

Every integer is a rational number since Q can be 1.

Hence, in the given options, 4 can be expressed as a simple fraction as 4/1. And all other options cannot be expressed as fractions.

Hence, 4 is a rational number in the given options.

3 586
Q:

Which expression is equivalent to $i233$?

 A) i B) 1 C) -i D) -1

Explanation:

We know that,

6 1847
Q:

The product of a number and its multiplicative inverse is

 A) 1 B) 0 C) -1 D) Infinity

Explanation:

The mutiplicative inverse of a number is nothing but a reciprocal of a number.

Now, the product of a number and its multiplicative inverse is always equal to 1.

For example :

Let the number be 15

Multiplicative inverse of 15 = 1/15

The product of a number and its multiplicative inverse is = 15 x 1/15 = 1.

2 1210
Q:

25 divided by 7

 A) 3.571 B) 35.71 C) 0.351 D) 0.0357

Explanation:

Here we have 25 divided by 7.

25 will not go directly in 7

Hence, we get the result in decimals.

25/7 = 3.571.

4 1088
Q:

Which of the following is not a prime number?

 A) 5 B) 11 C) 21 D) 37

Explanation:

A prime number is a whole number greater than 1 whose only factors are 1 and itself.

Factors of 5 are 1, 5

Factors of 11 are 1, 11

Factors of 21 are 1, 3, 7, 21

Factors of 37 are 1, 37.

Hence, according to the definition of a prime number, 21 is not a prime number as it has more than two factors.