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- Question
- If a 2 + b 2 = 234 and ab = 108, find the value of a + b / a - b .?
Options- A. 10
- B. 8
- C. 5
- D. 4
- Correct Answer
- 5
ExplanationWe know that, (a + b)2 = a2 + b2 + 2ab
= 234 + 2 x 108 = 450
(a - b)2 = a2 + b2 - 2ab
= 234 - 2 x 108 = 18
? (a + b)2/(a - b)2 = 450/18 = 25
? [(a + b)/(a - b)]2 = 25
? (a + b)/(a - b) = ?25 = 5 - 1. ? 132 + 28 / 4 - (3)3 + 107 = (?) 2
Options- A. 2
- B. 16
- C. 256
- D. 4 Discuss
- 2. Ravi earns twice as much in January as in each of the other months. What part of his annual earnings he earns in that month?
Options- A. 2/13
- B. 1/10
- C. 5/7
- D. 1/5 Discuss
- 3. In a family, the father took 1/4 of the cake and he had 3 times as much as others had. The total number of family members is?
Options- A. 3
- B. 7
- C. 10
- D. 12 Discuss
- 4. The highest score in an innings was 3/11 of the total and the next highest was 3/11 of the remainder. If the scores differed by 9, then the total score is?
Options- A. 99
- B. 110
- C. 121
- D. 132 Discuss
- 5. Gopal was asked to find 7/9 of a fraction. But he made a mistake of dividing the given fraction by 7/9 and got an answer which exceeded the correct answer by 8/21. The correct answer is?
Options- A. 3/7
- B. 7/12
- C. 2/21
- D. 1/3 Discuss
- 6. If a 2 + 1 = a, then the value of a 12 + a 6 + 1 is?
Options- A. 2
- B. 3
- C. -3
- D. 1 Discuss
- 7. If a, b and c are non-zero, a + 1/b = 1 and b + 1/c = 1, then the value of abc is?
Options- A. -3
- B. 1
- C. -1
- D. 3 Discuss
- 8. If a + b + c = 0, then the value of [(a + b)/c + (b + c)/a + (c + a)/b] x [a/(b + c) + b/(c + a) + c/(a + b)] is?
Options- A. 9
- B. 0
- C. 8
- D. -3 Discuss
- 9. If a + b + c = 14 and a 2 + b 2 + c 2 = 96, then (ab + bc + ca) =?
Options- A. 51
- B. 55
- C. 50
- D. 65 Discuss
- 10. [5 - [3/4 + {2 1/ 2 - (1/2 + 1/6 - 1/7)}]] / 2 =?
Options- A. 123/168
- B. 223/168
- C. 323/168
- D. 423/168 Discuss
Simplification problems
Search Results
Correct Answer: 4
Explanation:
(?)2 = ?132 + 28 / 4 - (3)3 + 107
= ?169 + 7 - 27 + 107
= ?256
= ?16
= 4
Correct Answer: 2/13
Explanation:
Suppose Ravi earns Rs. N in each of the 11 months.
Then earning in January = Rs. 2 x N.
? Total annual income = (11 x N + 2 x N) = Rs. 13 x N
Part of total earning in January = (2 x N) / (13 x N) = 2/13
Correct Answer: 10
Explanation:
Let there be N members, other than father .
Father's share = 1/4, other's share = 3/4.
Each of other's share = 3/4N
? 3 x 3/4N = 1/4
? N = 9
Hence, the total number of members = N + 1 = 10
Correct Answer: 121
Explanation:
Let total score be N.
Then highest score = 3N/11
Remainder = (N - 3N/11) = 8N/11
Next highest score = 3/11 of 8N/11 = 24N/121
Now, ? 3N/11 - 24N/121 = 9
? 9N/121 = 9
?N = 121
Correct Answer: 7/12
Explanation:
? Let the fraction = N
? (9 x N)/7 - (7 x N)/9 = 8/21
? (32 x N)/63 = 8/21
? N = (8/21) x (63/32) = 3/4
? Correct answer = N x 7/9 = 7/9 x 3/4 = 7/12
Correct Answer: 3
Explanation:
a2 + 1 = a
? a + 1/a = 1
On squaring both sides, we get
a2 + 1/a2 + 2 = 1
On cubing both sides, we get
(a2 + 1/a2)3 = (-1)3
? a6 + 1/a6 + 3a2 x 1/a2 (a2 + 1/a2) = -1
? a6 + 1/a6 + 3 x (-1) = -1
Now, a6 + 1/a6 + 1 = 3
As, a12 + a6 + 1 can be written as a6 + 1/a6 + 1
? a12 + a6 + 1 = 3
Correct Answer: -1
Explanation:
? a + 1/b = 1
ab + 1 = b ...(i)
Also, b + 1/c = 1
? b = 1 - 1/c ...(ii)
From Eqs. (i) and (ii), we get
ab + a = 1 - 1/c
? ab = -1/c
? abc = -1
Correct Answer: 9
Explanation:
Since, a + b + c = 0
Then, a + b = -c ....(i)
a + c = -b .........(ii)
b + c = -a ....(iii)
Now, [(a + b)/c + (b + c)/a + (c + a)/b] x [a/(b + c) + b/(c + a) + c/(a + b)]
Now, putting the value of a + b , b + c and c + a from Eqs. (i), (ii) and (iii) , we get
[(-c)/c + (-a)/a + (-b)/b] x [a/-a + b/-b + c/-c]
[(-1) + (-1) + (-1)] [(-1) + (-1) + (-1)]
= (-3) x (-3) = 9
Correct Answer: 50
Explanation:
We know that,
(a + b + c)2 = (a2 + b2 + c2) + 2(ab + bc + ca )
? 196 = 96 + 2(ab + bc + ca)
? 2(ab + bc + ca) = 196 - 96 = 100
? (ab + bc + ca) = 100/2 = 50
Correct Answer: 123/168
Explanation:
? = [5 -[3/4 + {21/2 - (1/2 + 1/6 - 1/7)}]]/2
= [5 - [3/4 + {5/2 -(1/2 + 7 - 6/42)}]]/2
= [5 - [3/4 + {5/2 - (1/2 + 1/42)}]]/2
= [5 - [3/4 + {5/2 - (21 + 1 /42)}]]/2
= [5 - [3/4 + {5/2 - 22/42}]]/2
= [5 - [3/4 + {105 - 22/42}]]/2
= [5 - [3/4 + 83/42]] / 2
= [5 - [63 + 166/84]]/2
= (191/84)/2
=191/168 = 123/168
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