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All questions of Inequalities for JAMB Exam

3x2 - 7x + 6 < 0
  • a)
    0.66 <x< 3    
  • b)
    -0.66 <x< 3
  • c)
    -1 < x < 3    
  • d)
    None of these
Correct answer is option 'D'. Can you explain this answer?

Avik Choudhury answered
At x = 0, inequality is not satisfied.
Hence, options (b), (c) and (d) are rejected. At x = 2, inequality is not satisfied. Hence, option (a) is rejected.
Thus, option (d) is correct.

For all integral values of x,
|x - 4| x< 5
  • a)
    -1 ≤x≤5    
  • b)
    1 ≤x≤5
  • c)
    -1 ≤ x ≤ 1    
  • d)
    x<5
Correct answer is option 'D'. Can you explain this answer?

Preeti Khanna answered
At x = 0 inequality is satisfied, option (b) is rejected.
At x = 2, inequality is satisfied, option (c) is rejected.
At x = 5, LHS = RHS.
Thus, option (d) is correct.

|x2 – 2x – 3| < 3x – 3
  • a)
    2 < x < 5
  • b)
    –2 < x < 5
  • c)
    x > 5
  • d)
    1 < x < 3
Correct answer is option 'A'. Can you explain this answer?

Yash Patel answered
x2 - 2x - 3 ≥ 0
(x-3) (x+1) ≥ 0
x belongs to (-∞,-3]∪[3,∞)
Therefore, x belongs to (-1,3)
=> x2 - 2x - 3 > 0
x2 - 2x - 3< 3x - 3
x2 - 5x < 0
x(x-5) < 0
x belongs to (0,5)........(1)
x2 - 2x - 3 < 0
x2 - 2x - 3 < 3x - 3
x2 + x - 6 > 0
(x+3)(x-2) > 0
x belongs to (-∞,-3]∪[2,∞)
x belongs to (2,3)........(2)
Taking intersection of (1) and (2)
we get,
x belongs to (2,5)
 

x2 - 7x + 12 < | x - 4 |
  • a)
    x < 2    
  • b)
    x > 4
  • c)
    2 < x < 4    
  • d)
    2 ≤ x ≤ 4
Correct answer is option 'C'. Can you explain this answer?

Harsh Jain answered
At x = 0, inequality is not satisfied, option (a) is rejected.
At x = 5, inequality is not satisfied, option (b) is rejected.
At x = 2 inequality is not satisfied.
Options (d) are rejected.
Option (c) is correct.

For x = 15, y = 10 and z = 9, find the value of le(x, min(y, x-z), le(9, 8, ma(x, y, z)).
  • a)
    5
  • b)
    9
  • c)
    12 
  • d)
    4
Correct answer is option 'B'. Can you explain this answer?

Sheetal patil answered

Explanation:

Given values:
x = 15
y = 10
z = 9

Calculations:
1. Find the minimum of y and x-z:
min(y, x-z) = min(10, 15-9) = min(10, 6) = 6

2. Find the maximum of x, y, and z:
ma(x, y, z) = max(15, 10, 9) = 15

3. Evaluate the expression:
le(x, min(y, x-z), le(9, 8, ma(x, y, z)) = le(15, 6, le(9, 8, 15))

4. Compare 9 and 8:
le(9, 8) = 0 (as 9 is not less than 8)

5. Evaluate the expression further:
le(15, 6, 0) = 6

Therefore, the value of le(x, min(y, x-z), le(9, 8, ma(x, y, z)) for the given values is 6, which corresponds to option 'b'.

p, q and r are three non-negative integers such that p + q + r = 10. The maximum value of pq + qr + pr + pqr is
  • a)
    ≥ 60 and < 70
  • b)
    ≥ 50 and < 60
  • c)
    ≥ 40 and < 50
  • d)
    ≥ 70 and < 80
Correct answer is option 'A'. Can you explain this answer?

The product of 2 numbers A and B is maximum when A = B.
If we cannot equate the numbers, then we have to try to minimize the difference between the numbers as much as possible.
pq will be maximum when p=q.
qr will be maximum when q=r.
qr will be maximum when r=p.
Therefore, p, q, and r should be as close to each other as possible.
We know that p,q,and r are integers and p + q + r = 10.
=> p,q, and r should be 3, 3, and 4 in any order.
Substituting the values in the expression, we get,
pq + qr + pr + pqr = 3*3 + 3*4 + 3*4 + 3*3*4
= 9 + 12 + 12 + 36
= 69

x, y and z are three positive integers such that x > y > z. Which of the following is closest to the product xyz?
  • a)
    (x - 1)yz
  • b)
    x(y - 1)z
  • c)
    xy(z - 1)
  • d)
    x(y + 1)z
Correct answer is option 'A'. Can you explain this answer?

Gaurav Patel answered
Explanation:

Given:
x, y, and z are three positive integers such that x > y > z.

To find:
The expression closest to the product xyz.

Solution:

Approach:
To find the closest expression to the product xyz, we need to consider the given condition x > y > z.
- We know that x is the largest among x, y, and z. So, the closest expression to xyz would be when we replace x with (x - 1) to get a smaller value.
- This is because if we replace x with (x - 1), the product xyz will decrease, making it closer to the actual value.

Calculations:
Let's consider option A: (x - 1)yz
- If we substitute x with (x - 1), the expression becomes: (x - 1)yz
- The product of this expression is: (x - 1) * y * z
- This expression will be closest to the product xyz because we are replacing the largest value x with (x - 1), making the product smaller.
Therefore, option A: (x - 1)yz is the closest to the product xyz.

3x2 - 7x + 4 ≤ 0
  • a)
    x > 0    
  • b)
    x < 0
  • c)
    All x    
  • d)
    None of these
Correct answer is option 'D'. Can you explain this answer?

At x = 0, inequality is not satisfied. Thus, option (c) is rejected. Also x = 0 is not a solution of the equation. Since, this is a continuous function, the solution cannot start from 0. Thus options (a) and (b) are not right. Further, we see that the given function is quadratic with real roots. Hence, option (d) is also rejected.

What is the value of ma(10, 4, le((la10, 5, 3), 5, 3))?
  • a)
     7
  • b)
     6.5
  • c)
     8
  • d)
     7.5
Correct answer is option 'B'. Can you explain this answer?

To solve the given expression ma(10, 4, le((la10, 5, 3), 5, 3)), we need to follow the order of operations (also known as PEMDAS/BODMAS).

Step 1: Evaluate the innermost expression
The innermost expression is le((la10, 5, 3), 5, 3). Let's break it down further:
- la10 means the largest among 10, 5, and 3, which is 10.
- le(10, 5, 3) means the smallest among 10, 5, and 3, which is 3.

So, the innermost expression evaluates to 3.

Step 2: Substitute the innermost expression in the main expression
Now, we substitute the value of the innermost expression (3) in the main expression: ma(10, 4, 3).

Step 3: Evaluate the main expression
The expression ma(10, 4, 3) means the arithmetic mean (average) of the three numbers: 10, 4, and 3.

Arithmetic Mean Formula: sum of numbers/total number of numbers

Sum of numbers = 10 + 4 + 3 = 17
Total number of numbers = 3

Arithmetic Mean = 17/3 = 5.67

Rounded to one decimal place, the value of ma(10, 4, 3) is 5.7.

Step 4: Corresponding option
The correct option given is 'B' which states the value as 6.5. However, this does not match the calculated value of 5.7. Hence, the correct option should be re-evaluated or reviewed, as it does not match the calculated value.

The number of positive integer valued pairs (x, y), satisfying 4x – 17 y = 1 and x < 1000 is:
  • a)
    55
  • b)
    57
  • c)
    59
  • d)
    58
Correct answer is option 'C'. Can you explain this answer?

EduRev CLAT answered

The integral values of x for which y is an integer are 13, 30, 47,……
The values are in the form 17n + 13, where n ≥ 0
17n + 13 < 1000
⇒ 17n < 987
⇒ n < 58.05
⇒ n can take values from 0 to 58
⇒ Number of values = 59

|x2 + x| – 5 < 0
  • a)
    x < 0
  • b)
    x > 0
  • c)
    None of these
  • d)
    All values of x
Correct answer is option 'C'. Can you explain this answer?

Sinjini Gupta answered
At x = 0 inequality is satisfied.
Thus, options (a), (b), and (d) are rejected.
Option (c) is correct.
 

|x2 - 2x| < x
  • a)
    l < x < 3    
  • b)
    —1 < x < 3
  • c)
    0 < x < 4    
  • d)
    x > 3
Correct answer is option 'A'. Can you explain this answer?

Aarav Sharma answered
The expression |x2 - 2x| represents the absolute value of the quadratic expression x^2 - 2x.

To find the absolute value of x^2 - 2x, we need to consider the cases when the expression inside the absolute value is positive and negative.

When x^2 - 2x is positive (greater than or equal to zero):
x^2 - 2x ≥ 0
x(x - 2) ≥ 0

In this case, the absolute value of x^2 - 2x is simply x^2 - 2x.

When x^2 - 2x is negative (less than zero):
x^2 - 2x < />
x(x - 2) < />

In this case, the absolute value of x^2 - 2x is -(x^2 - 2x), which is equal to -x^2 + 2x.

Therefore, the expression |x^2 - 2x| can be written as:

x^2 - 2x, for x ≤ 0 or x ≥ 2
-x^2 + 2x, for 0 < x="" />< 2="" />

x2 – 14x – 15 > 0
  • a)
    x < –1
  • b)
    15 < x
  • c)
    Both (a) and (b)
  • d)
    –1 < x < 15
Correct answer is option 'C'. Can you explain this answer?

Aarav Sharma answered
I'm sorry, I don't understand the context of your message. Can you please provide more information or clarify your request?

3x2 – 7x – 6 < 0
  • a)
    –0.66 < x < 3
  • b)
    x < – 0.66 or x > 3
  • c)
    3 < x < 7
  • d)
    –2 < x < 2
Correct answer is option 'A'. Can you explain this answer?

Gargi Kulkarni answered
At x = 0, inequality is satisfied. Hence, options (b) and (c) are rejected. x = 3 gives LHS = RHS.
and x = – 0.66 also does the same. Hence. roots of the equation are 3 and – 0.66.
Thus, option (a) is correct.

x2 – 7x + 12 < |x – 4|
  • a)
    x < 2
  • b)
    x > 4
  • c)
    2 < x < 4
  • d)
    2 £ x £ 4
Correct answer is option 'C'. Can you explain this answer?

Prisha Shah answered
At x = 0, inequality is not satisfied, option (a) is rejected.
At x = 5, inequality is not satisfied, option (b) is rejected.
At x = 2 inequality is not satisfied.
Options (d) are rejected.
Option (c) is correct

|x – 6| > x2 – 5x + 9
  • a)
    1 £ x < 3
  • b)
    1 < x < 3
  • c)
    2 < x < 5
  • d)
    –3 < x < 1
Correct answer is option 'B'. Can you explain this answer?

Atharva Khanna answered
At x = 2, inequality is satisfied.
At x = 0, inequality is not satisfied.
At x = 1, inequality is not satisfied but LHS = RHS.
At x = 3, inequality is not satisfied but LHS = RHS.
Thus, option (b) is correct.
Solve other questions of LOD I and LOD II in the same fashion.

|x - 6| > x2 - 5x + 9
  • a)
    1 ≤ x < 3    
  • b)
    1 < x < 3
  • c)
    2 < x < 5    
  • d)
    -3 < x < 1
Correct answer is option 'B'. Can you explain this answer?

Shail Jain answered
At x = 2, inequality is satisfied.
At x = 0, inequality is not satisfied.
At x = 1, inequality is not satisfied but LHS = RHS. At x = 3, inequality is not satisfied but LHS = RHS. Thus, option (b) is correct.
Solve other questions of LOD I and LOD II in the same fashion.

If a, b, c and d are four positive real numbers such that abcd = 1, what is the minimum value of (1 + a)(1 + b)(1 + c)(1+ d)?
  • a)
    16
  • b)
    1
  • c)
    4
  • d)
    18
Correct answer is option 'A'. Can you explain this answer?

Since the product is constant, (a + b + c + d)/4 > = (abcd)1/4
We know that abcd = 1.
Therefore, a + b + c + d > = 4
(a + 1)(b + 1)(c + 1)(d + 1)
= 1 + a + b + c + d + ab + ac + ad + bc + bd + cd + abc + bed + cda + dab + abcd
We know that abcd = 1
Therefore, a = 1/bcd, b = 1/acd, c = 1/bda and d = 1/abc
Also, cd = 1/ab, bd = 1/ac, bc = 1/ad
The expression can be clubbed together as
1 + abcd + (a+1/a)+(b+1/b)+(c+1/c)+(d+1/d) + (ab+1/ab) + (ac+1/ac) + (ad +1/ad)
For any positive real number x, x + 1/x ≥ 2
Therefore, the least value that (a+1/a), (b+1/b).... (ad + 1/ad) can take is 2.
(a+1)(b+1)(c+1)(d+1) > 1 + 1 + 2 + 2 + 2 + 2 + 2 + 2 + 2
=> (a + 1)(b + 1)(c + 1)(d + 1) ≥ 16
The least value that the given expression can take is 16.

The number of integers n satisfying -n + 2 ≥ 0 and 2n ≥ 4 is
  • a)
    1
  • b)
    0
  • c)
    2
  • d)
    3
Correct answer is option 'A'. Can you explain this answer?

First inequality:
-n + 2 ≥ 0
-n ≥ -2
n ≤ 2
Second inequality:
2n ≥ 4
n ≥ 2
Only n = 2 satisfies both inequalities. So, there is only 1 integer that satisfies both the inequalities.
The correct option is A.

If x, y and z are real numbers such that x + y + z = 5 and xy + yz + zx = 3, what is the largest value that x can have?
  • a)
    5/3
  • b)
    13/3
  • c)
    √19
  • d)
    None of these
Correct answer is option 'B'. Can you explain this answer?

The given equations are  x + y + z = 5 — (1) , xy + yz + zx = 3 — (2)
xy + yz + zx = 3
x(y + z) + yz = 3
⇒ x ( 5 - x ) +y ( 5 – x – y) = 3
⇒ -y2 - y(5 - x) - x2 + 5x = 3
⇒ y2 + y(x - 5) + (x- 5x + 3) = 0
The above equation should have real roots for y, => Determinant >= 0
⇒ b2 - 4ac0
⇒ (x - 5)2 - 4(x2 - 5x + 3) ≥ 0
⇒ 3x2 - 10x - 13 ≤ 0
⇒ -1 ≤ x ≤ 13/3
Hence maximum value x can take is 13/3, and the corresponding values for y,z are 1/3, 1/3

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