Discussion
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- Question
If a, b, c are real and a3 + b3 + c3 = 3abc and a + b + c ≠ 0 , then the relation between a, b, c will be
Options- A. a + b = c
- B. a + c = b
- C. a = b = c
- D. b + c = a
- Correct Answer
- a = b = c
ExplanationGiven that :-
Now ,a3 + b3 + c3 = 3abc
( a+b+c )( a2 + b2 + c2 - ab - bc - ca ) + 3abc = 3abc
( a+b+c )( a2 + b2 + c2 - ab - bc - ca ) = 0
∴ a² + b² + c² - ab - bc - ca = 0 or a + b + c ≠ 0
Where ,
a = b = c - 1.
If 5a + 1 = 5, the value of 9a2 + 1 is 3a 25a2
Options- A. 34 5
- B. 39 5
- C. 42 5
- D. 52 5 Discuss
- 2.
If x = 2 + ?3, then the value of ?x + 1 is : ?x
Options- A. ?3
- B. ?6
- C. 2 ?6
- D. 6 Discuss
- 3. If a3 ? b3 = 56 and a ? b = 2, then the value of ( a2 + b2 ) is :
Options- A. ? 10
- B. ? 12
- C. 20
- D. 18 Discuss
- 4.
If (5x2 ? 3y2) : xy = 11 : 2, then the positive value of x is : y
Options- A. 7 2
- B. 5 2
- C. 3 2
- D. 5 3 Discuss
- 5. If P = (0.08) 2, Q = 1/(0.08) 2 and R = (1 ? 0.08) 2 ? 1, then out of the following the true relation is
Options- A. Q < P and P = R
- B. P < Q and P = R
- C. Q < R < P
- D. R < P < Q Discuss
- 6. The line passing through the points (? 2, 8) and (5, 7)
Options- A. does not cut any axes
- B. cuts x- axis only
- C. cuts y - axis only
- D. cuts both the axes Discuss
- 7. If the difference of two numbers is 3 and the difference of their squares is 39; then the larger number is:
Options- A. 9
- B. 12
- C. 13
- D. 8 Discuss
- 8. Let a = ?6 - ?5, b = ?5 - 2, c = 2 - ?3 Then point out the correct alternative among the four alternatives given below.
Options- A. a < b < c
- B. b < a < c
- C. a < c < b
- D. b < c < a; Discuss
- 9. If a2 + b2 + c2 = 2 (a ? b ? c) ? 3, then the value of 2a ? 3b + 4c is
Options- A. 1
- B. 7
- C. 2
- D. 3 Discuss
- 10. If the square of the sum of two numbers is equal to 4 times of their product. then the ratio of these numbers is:
Options- A. 2 : 1
- B. 1 : 3
- C. 1 : 1
- D. 1 : 2 Discuss
Elementary Algebra problems
Search Results
Correct Answer: 39 5
Explanation:
Correct Answer: ?6
Explanation:
Correct Answer: 20
Explanation:
As we know from the algebra formula,
(a ? b)3 = a3 ? b 3 ? 3ab (a ? b) .......................(1)
As per given question,
a3 ? b 3 = 56 and a ? b = 2
Put these value in above equation (1) . We will get,
? 23 = 56 ? 3ab x 2
? 8 = 56 ? 3ab x 2
? 8 = 56 ? 6ab
? 6ab = 56 ? 8 = 48
? ab = 8 ...................... (i)
? a2 + b2 = (a ? b)2 + 2ab
? a2 + b2 = (a ? b)2 + 2ab
Put the value of
? a2 + b2 = 22 + 2 x 8
? a2 + b2 = 4 + 16 = 20
Correct Answer: 3 2
Explanation:
Correct Answer: R < P < Q
Explanation:
Correct Answer: cuts y - axis only
Explanation:
As indicated in the graph, the line passing through the points cuts Y-axis only.
Correct Answer: 8
Explanation:
Let the numbers are p and q.
p ? q = 3 ? (1)
p2 ? q2 = 39
(p ? q) (p + q) = 39 ? x + y = 13 ? (2)
Adding eqn (1) and (2)
p + q + p ? q = 16 ? p = 8
? q = 3
Hence, 8 is the larger number.
Correct Answer: a < b < c
Explanation:
We know that , ?6 = 2.44, ?5 = 2.23, ?3 = 1.73
a = ?6 - ?5 = 2.44 - 2.23 = 0.21
b = ?5 - 2 = 2.23 - 2 = 0.23
c = 2 - ?3 = 2 - 1.73 = 0.27
Correct Answer: 1
Explanation:
Given that :- a2 + b2 + c2 = 2 (a ? b ? c) ? 3
? a2 + b2 + c2 - 2 (a ? b ? c) + 3 = 0
? a2 + b2 + c2 - 2a + 2b + 2c + 3 = 0
? ( a2 + 1 - 2a ) + ( b2 + 1 + 2b ) + ( c2 + 1 + 2c ) = 0
? ( a - 1 )2 + ( b + 1 )2 + ( c + 1 )2 = 0
This is possible when ( a - 1 )2 = 0, ( b + 1 )2 = 0, and ( c + 1 )2 = 0
? a = 1, b = ?1, c = ?1
Thus, 2a ? 3b + 4c = 2 (1) ? 3 (?1) + 4 (?1)
2a ? 3b + 4c = 2 + 3 ? 4 = 1.
Correct Answer: 1 : 1
Explanation:
Let the number be p and q.
According to question,
(p + q)2 = 4pq
? p2 + q2 + 2pq ? 4pq = 0
? (p ? q)2 = 0
? p = q
Hence , required ratio is 1 : 1 .
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