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- Question
- If x + 1/x = 3, then x5 + 1/x5 is equal to?
Options- A. 123
- B. 83
- C. 92
- D. 112
- Correct Answer
- 123
Explanationx + 1/x = 3 ........................ (i)
On squaring both side, we will get
(x + 1/x)2 = (3)2
Use the Square algebra formula (a + b)2 = a2 + 2ab + b2
? x2 + 1/x2 + 2 = 9
? x2 + 1/x2 = 7 ..................(ii)
Again squaring both sides, we will get
(x2 + 1/x2)2 = (7)2
Use the Square algebra formula (a + b)2 = a2 + 2ab + b2
? x4 + 1/4 + 2 = 49
? x4 + 1/x4 = 47 .....................(iii)
On cubing the equation (i) both side, we will get
(x + 1/x)3 = (3)3
Use the cube algebra formula (a + b)3 = a3 + 3a2b + 3ab2 + b3
? x3+ 1/x3 + 3(x + 1/x) = 27
? x3 + 1/x3 + 9 = 27 [? (x + 1/x) = 3]
? x3 + 1/x3 = 18 ...................(iv)
On multiplying Eqs. (i) and (iii) , we get
? (x4 + 1/x4) (x + 1/x) = 47 x 3
? x5 + 1/x5 + x3 + 1/x3 = 141
? x5 + 1/x5 + 18 = 141 [from Eq. (iv)]
? x5 + 1/x5 = 123 - 1. If the Price of 6 toys is Rs. 264.37, What will be the approximate price (Rs) of 5 toys?
Options- A. 230
- B. 120
- C. 320
- D. 220 Discuss
- 2. A runs 1 2/ 3 times as fast as B. If A gives B a start of 40 m, how far must the winning post be, so that A and B might reach it at the same time?
Options- A. 75 m
- B. 200 m
- C. 100 m
- D. 125 m Discuss
- 3. A person rows a kilometre down the stream in 10 minute and upstream in 30 minutes. Find the velocity of the stream?
Options- A. 1 km/hr
- B. 2 km/hr
- C. 3 km/hr
- D. 4 km/hr Discuss
- 4. One year ago the ratio between Samir and Ashok's age was 4 : 3. One years Later the sum of their ages will be 5 : 4. What is the sum of their present ages in years?
Options- A. 12 years
- B. 15 years
- C. 16 years
- D. Cannot be determined Discuss
- 5. What is 786 time of 964?
Options- A. 759276
- B. 749844
- C. 75416
- D. 757704 Discuss
- 6. The percent profit when an article is sold for Rs. 78 is twice as when it is sold for Rs. 69. The C.P. of the article is?
Options- A. Rs. 49
- B. Rs. 51
- C. Rs. 57
- D. Rs. 60 Discuss
- 7. In a game of 100 points, A scores 100 points while B scores only 65 points. In this game, how much points can A give to B?
Options- A. 45
- B. 35
- C. 25
- D. 55 Discuss
- 8. Find the value of log 8 + log 1/8?
Options- A. 0
- B. 1
- C. 2
- D. log (64) Discuss
- 9. Given log 10 2 = 0.30103, log 10 3 = 0.47712. Find the number of digit, in 3 12 x 2 8?
Options- A. 6
- B. 7
- C. 8
- D. 9 Discuss
- 10. Find the product of place value and face value of 5 in 65231
Options- A. 28000
- B. 25000
- C. 27000
- D. 26000 Discuss
More questions
Correct Answer: 220
Explanation:
Given in the question,
Price of 6 toys is Rs. 264.37.
? Price of 1 toys is Rs. 264.37/ 6 .
? Price of 5 toys is Rs. 264.37 x 5 / 6 .
? Price of 5 toys is Rs. 44 x 5 .
? Price of 5 toys is Rs. 220.
Correct Answer: 100 m
Explanation:
Ratio of the speeds of A and B = 5 : 3
Thus, in a race of 5m, A gains 2 m over B.
2 m are gained by A in a race of 5 m.
40 m will be gained by A in a race of (5/2) x 40 m = 100 m
? Winning post is 100 m away from the starting point.
Correct Answer: 2 km/hr
Explanation:
Velocity of stream = (downstream velocity - upstream velocity)/2
= (60/10 - 60/30)/2
= 2 km/hr
Correct Answer: 16 years
Explanation:
Let their ages one years ago be 4x and 3x years.
? (4x + 2)/(3x + 2) = 5 / 4
? 4(4x + 2) = 5(3x + 2)
? x = 2
? Sum of their present ages = (4x + 1) + (3x + 1) = 16 years
Correct Answer: 757704
Explanation:
Required number
= 786 x 964 = 757704
Correct Answer: Rs. 60
Explanation:
Let the C.P. be Rs. x
Then 2(69 - x) / 100 = (78 - x) / 100
? 138 - 2x = 78 - x
? x = 60
? C.P. = Rs. 60
Correct Answer: 35
Explanation:
Score of A = 100 points
Score of B = 65 points
? A can give (100 - 65 ) = 35 points to B.
Correct Answer: 0
Explanation:
Given expression = log 8 + log (1/8)
= log 8 x (1/8)
= log 1
= 0
Correct Answer: 9
Explanation:
Let N = 312 x 28
? log N = 12 x log3 + 8 x log 2
? log N = 12 x 0.47712 + 8 x 0.30103
? log N = 8.13368
? No.of digits = 8 + 1 = 9
Correct Answer: 25000
Explanation:
Place value of 5 in 65231 = 5 x 1000
= 5000
Face value = 5
required product = 5000 x 5 = 25000
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