Discussion
Home ‣ Aptitude ‣ Quadratic Equation Comments
- Question
- Determine k such that the quadratic equation x2 - 2( 1 + 3k ) x + 7 ( 3 + 2k ) = 0 has equal roots.
Options- A. 2, - 10 9
- B. 2, 10 9
- C. - 2, 10 9
- D. - 2, -10 9
- Correct Answer
- 2, - 10 9
Explanation
- 1. If ?, ? are the roots of the equation x2 + kx + 12 = 0 such that ? ? ? = 1, the value of k is
Options- A. 0
- B. ± 5
- C. ± 1
- D. ± 7 Discuss
- 2. The positive value of m for which the roots of the equation 12x2 + mx + 5 = 0 are in the ratio 3 : 2 is :
Options- A. 5?10
- B. 5 ?10 2
- C. 5 12
- D. 12 5 Discuss
- 3. The value of k for which the roots ?, ? of the equation : x2 ? 6x + k = 0 satisfy the relation 3? + 2? = 20, is
Options- A. 8
- B. - 8
- C. 16
- D. - 16 Discuss
- 4. ?. 24x 2 + 38x + 15 = 0
?.12y 2 + 28y + 15 = 0
Options- A. x ? y
- B. x > y
- C. x ? y
- D. x < y Discuss
- 5. ?. 3x 2 ? 20x ?32 = 0
?. 2y 2 ? 3y ? 20 = 0
Options- A. x < y
- B. x ? y
- C. x > y
- D. Relationship between x and y cannot be established Discuss
- 6. If ? and ? are the roots of the equation x2 - 3?x + ?2 = 0,
find ? if ?2 + ?2 = 7 4
Options- A. ± 1 2
- B. ± ?7 2
- C. ± ?3 2
- D. None of these Discuss
- 7. If a and b are the roots of the equation x 2 - 6x + 6 = 0, find the value of 2(a 2 + b 2).
Options- A. 40
- B. 42
- C. 48
- D. 46 Discuss
- 8. If ? and ? be the roots of the equation ax 2 + bx + c = 0, find the value of ? 2/? + ? 2/? .
Options- A. ab -b2c/2b2c
- B. 3bc - a3/b2c
- C. 3ac - b2/a3c
- D. 3abc - b3/a2c Discuss
- 9. If ? and ? are the roots of the equation x 2 - 11x + 24 = 0, find the equation having the roots ? + 2 and ? + 2
Options- A. x2 + 15x + 24 = 0
- B. x2 - 15x + 24 = 0
- C. x2 + 15x - 50 = 0
- D. x2 + 15x - 60 = 0 Discuss
- 10. If x 2 = 6 + ? 6 + ?6 + ?6 + .... ? , then what is one of the value of x equal to?
Options- A. 6
- B. 5
- C. 4
- D. 3 Discuss
Quadratic Equation problems
Search Results
Correct Answer: ± 7
Explanation:
As per the given above question , we know that
Let, ?, ? be the roots of the equation x2 + kx + 12 = 0
? ? + ? = ?k and ?? = 12
Now ( ? - ? )2 = ( ? + ? )2 - 4??
( 1 )2 = k2 - 4(12)
? k2 = 49 ? k = ± 7.
Correct Answer: 5?10
Explanation:
Correct Answer: 8
Explanation:
According to question , we have
The roots ?, ? of the equation : x2 ? 6x + k = 0
On comparing with ax2 + bx + c = 0 , we get a = 1 , b = - 6 , c = k
Now , ? + ? = ( - b/a ) = 6
? + ? = 6 and 3? + 2? = 20
On solving ,
? ? = 4, ? = 2
Product of the roots = k
So, k = ?? = 4 × 2 = 8.
Hence , required answer will be option A .
Correct Answer: x ? y
Explanation:
Correct Answer: Relationship between x and y cannot be established
Explanation:
Correct Answer: ± 1 2
Explanation:
Correct Answer: 48
Explanation:
a and b are the roots of the equation
x2 - 6x + 6 = 0
? a + b = -B/A = 6 and ab = C/A = 6
We know that,
a2 + b2 = (a + b)2 - 2ab
= (6)2 - 2 x 6 = 36 - 12 = 24
? 2(a2 + b2) = 2 x 24 = 48
Correct Answer: 3abc - b3/a2c
Explanation:
Given, ? and ? are the roots of the equation ax2 + bx + c = 0
? Sum of two roots = -b/a
? + ? = -b/a
and product of two roots = c/a
? ? = c/a
? ?2/? + ?2/? = ( ?3 + ?3) / ? ?
= [(? + ?) 3 - 3 ? ? (? + ?)] / ??
[? (a + b)3 = a3 + b3 + 3ab(a + b) ]
= (-b/a)3 - [3c/a(-b/a)/c/a = -b3/a3 + 3bc/a2]/(c/a)
= 3abc - b3/a2c
Correct Answer:
Explanation:
Given equation is
x2 - 11x + 24 = 0
Then, required equation is
(x - 2)2 - 11(x - 2) + 24 = 0
? x2 - 4x + 4 - 11x + 22 + 24 = 0
? x2 - 15x + 50 = 0
Correct Answer: 3
Explanation:
Here, x2 = 6 + ?6 + ?6 + ?6 + .... ? ,
So, x2 = 6 + ?x2
? x2 = 6 + x
? x2 - x - 6 = 0
? x2 + 2x - 3x - 6 = 0
? x(x + 2) - 3(x + 2) = 0
? (x - 3) (x + 2) = 0
? x = 3
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