4
Q:

 (3x + 2) (2x - 5) = ax² + kx + n .

What is the value of a - n + k ?

A) 5 B) 8
C) 9 D) 10

Answer:   A) 5



Explanation:

This is a quadratic equation. To find n we multiply the last terms in each bracket together (2 times -5) = -10

To find ‘a’ we multiply the first terms in each bracket together (3x times 2x) = 6x2, So a = 6.

Thus a - n = 16

To find k we multiply the first term in the first bracket by the second term in the second bracket and add the result to the product of the second term in the first bracket and the first term in the second. (-15x + 4x) = -11x. So k = -11

16 - 11 = 5

Subject: Problems on Numbers
Exam Prep: GRE
Q:

A natural number, when divided by 4, 5, 6 or 7, leaves a remainder of 3 in each case. What is the smallest of all such numbers?

A) 63 B) 423
C) 843 D) 213
 
Answer & Explanation Answer: B) 423

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1 597
Q:

The square root of which of the following numbers is irrational?

A) 3969 B) 5625
C) 6560 D) 1764
 
Answer & Explanation Answer: C) 6560

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0 601
Q:

What is the mean of first hundred natural numbers?

A) 50 B) 50.5
C) 51.5 D) 51
 
Answer & Explanation Answer: B) 50.5

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1 681
Q:

For what value of 'y', x2 + 112x + y2 is a perfect square?

A) 1/24 B) 1/12
C) 1/6 D) 1/3
 
Answer & Explanation Answer: A) 1/24

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0 827
Q:

If a number 657423547X46 is divisible by 11, then find the value of X.

 

A) 7 B) 9
C) 8 D) 6
 
Answer & Explanation Answer: B) 9

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1 7627
Q:

What will be the maximum power of 8 that exactly divides 25!?

A) 6 B) 7
C) 8 D) 9
 
Answer & Explanation Answer: B) 7

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0 801
Q:

Calculate the difference between the square of the largest and smallest two-digit prime numbers.

A) 9298 B) 9892
C) 9292 D) 9288
 
Answer & Explanation Answer: D) 9288

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0 674
Q:

Find the greatest four digit number when divided by 8, 12, 16 leaves 2 as remainder in every case?

A) 9984 B) 9985
C) 9986 D) 9987
 
Answer & Explanation Answer: C) 9986

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0 714