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Quiz
Quadratic Equations
Score: 0/10
1. Solve for x : 3x 2 + 18x - 81 = 0
1. Solve for x : 3x 2 + 18x - 81 = 0
1. Solve for x :
3x 2 + 18x - 81 = 0
A.
x = 9 or x = - 9
B.
x = 3 or x = - 9
C.
x = 3 or x = - 27
D. None of the above
2. Solve for x : 12x 2 - 11x + 2 = 0
2. Solve for x : 12x 2 - 11x + 2 = 0
2. Solve for x :
12x 2 - 11x + 2 = 0
A.
x = 4 or x =
B.
x = 1 or x = 2
C.
x = or x =
D. None of the above
3. Solve for x : 2x ( 3x + 5 ) = 11
3. Solve for x : 2x ( 3x + 5 ) = 11
3. Solve for x :
2x ( 3x + 5 ) = 11
A.
x = or x =
- 5 -
91
6
B.
x =
5 +
91
6
or x =
5 -
91
6
C.
x = - 5 or x = 5
D. None of the above
4. Solve for x by completing the square: 2x 2 + x - 8 = 0
4. Solve for x by completing the square: 2x 2 + x - 8 = 0
4. Solve for x by completing the square:
2x 2 + x - 8 = 0
A.
x =
1 +
65
4
or x =
1 -
65
4
B.
x =
- 1 +
65
4
or x =
- 1 -
65
4
C.
x = - 1 or x = 1
D. None of the above
5. Solve for x by completing the square: - 2x 2 - 2x +
2
3
= 0
5. Solve for x by completing the square: - 2x 2 - 2x +
2
3
= 0
5. Solve for x by completing the square:
- 2x 2 - 2x +
2
3
= 0
A.
x =
- 3 +
21
6
or x =
- 3 -
21
6
B.
x = 3 or x = - 3
C.
x =
3 +
21
6
or x =
3 -
21
6
D. None of the above
6. Solve for x by completing the square: x 2 - 6x - 39 = 0
6. Solve for x by completing the square: x 2 - 6x - 39 = 0
6. Solve for x by completing the square:
x 2 - 6x - 39 = 0
A.
x =
- 3 + 4
3
or x = - 3 - 4
3
B.
x =
3 + 4
3
or x = 3 - 4
3
C.
x = 9 or x = - 9
D. None of the above
7. Solve the following inequality : 5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
7. Solve the following inequality : 5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
7. Solve the following inequality :
5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
A.
x ≤
3
5
or x ≥ 7
B.
3
5
≤ x ≤ 7
C.
x ≥
3
5
or x ≥ 7
D. None of the above
8. Solve the following inequality : - 15x 2 + x + 40 ≤ 0
8. Solve the following inequality : - 15x 2 + x + 40 ≤ 0
8. Solve the following inequality :
- 15x 2 + x + 40 ≤ 0
A.
-
5
3
≤ x ≤
8
5
B.
-
8
5
≤ x ≤
5
3
C.
x ≤ -
8
5
or x ≥
5
3
D. None of the above
9. Solve the following inequality : 8x ( x + 1 ) ≥ 4 ( 9 - x )
9. Solve the following inequality : 8x ( x + 1 ) ≥ 4 ( 9 - x )
9. Solve the following inequality :
8x ( x + 1 ) ≥ 4 ( 9 - x )
A.
- 3 ≤ x ≤
3
2
B.
- 3 ≥ x ≥
3
2
C.
x ≤ - 3 or x ≥
3
2
D. None of the above
10. Solve the following inequality : 5x ( 4x + 5 ) < 4 ( x - 1 )
10. Solve the following inequality : 5x ( 4x + 5 ) < 4 ( x - 1 )
10. Solve the following inequality :
5x ( 4x + 5 ) < 4 ( x - 1 )
A.
-
4
5
< x < -
1
4
B.
1
4
< x <
4
5
C.
x < -
4
5
or x > -
1
4
D. None of the above
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Solutions
Quadratic Equations
Question 1 of 10
1. Solve for x : 3x 2 + 18x - 81 = 0
1. Solve for x : 3x 2 + 18x - 81 = 0
1. Solve for x :
3x 2 + 18x - 81 = 0
A.
x = 9 or x = - 9
B.
x = 3 or x = - 9
C.
x = 3 or x = - 27
D. None of the above
Correct Answer
Option B
Detailed Solution
Solution Details
Given 3x 2 + 18x - 81 = 0
• 3x 2 + 18x - 81 = x 2 + 6x - 27 = 0
• ( x - 3 ) ( x + 9 ) = 0
• ( x - 3 ) = 0 or ( x + 9 ) = 0
∴ x = 3 or x = - 9
For more info please see
Quadratic Equations
Quadratic Equations
Question 2 of 10
2. Solve for x : 12x 2 - 11x + 2 = 0
2. Solve for x : 12x 2 - 11x + 2 = 0
2. Solve for x :
12x 2 - 11x + 2 = 0
A.
x = 4 or x =
3
2
B.
x = 1 or x = 2
C.
x =
1
4
or x =
2
3
D. None of the above
Correct Answer
Option C
Detailed Solution
Solution Details
Given 12x 2 - 11x + 2 = 0
• 12x 2 - 11x + 2 = 0
• ( 4x - 1 ) ( 3x - 2 ) = 0
• ( 4x - 1 ) = 0 or ( 3x - 2 ) = 0
∴ x =
1
4
or x =
2
3
For more info please see
Quadratic Equations
Quadratic Equations
Question 3 of 10
3. Solve for x : 2x ( 3x + 5 ) = 11
3. Solve for x : 2x ( 3x + 5 ) = 11
3. Solve for x :
2x ( 3x + 5 ) = 11
A.
x =
- 5 +
91
6
or x =
- 5 -
91
6
B.
x =
5 +
91
6
or x =
5 -
91
6
C.
x = - 5 or x = 5
D. None of the above
Correct Answer
Option A
Detailed Solution
Solution Details
Given 2x ( 3x + 5 ) = 11
• 2x ( 3x + 5 ) = 11
• 6x 2 + 10x - 11 = 0
• x =
– b ±
b 2 – 4ac
2a
The equation cannot be factorised so we use the quadratic formula
• x =
– 10 ±
( 10 ) 2 – 4 ( 6 ) ( - 11 )
2 ( 6 )
=
– 10 ±
364
12
=
– 10 ± 2
91
12
=
– 5 ±
91
6
∴ x =
– 5 +
91
6
or x =
– 5 –
91
6
For more info please see
Quadratic Equations
Given 2x ( 3x + 5 ) = 11
• 2x ( 3x + 5 ) = 11
• 6x 2 + 10x - 11 = 0
• x =
– b ±
b 2 – 4ac
2a
The equation cannot be factorised so we use the quadratic formula
• x =
– 10 ±
( 10 ) 2 – 4 ( 6 ) ( - 11 )
2 ( 6 )
=
– 10 ±
364
12
=
– 10 ± 2
91
12
=
– 5 ±
91
6
∴ x =
– 5 +
91
6
or x =
– 5 –
91
6
For more info please see
Quadratic Equations
Quadratic Equations
Question 4 of 10
4. Solve for x by completing the square: 2x 2 + x - 8 = 0
4. Solve for x by completing the square: 2x 2 + x - 8 = 0
4. Solve for x by completing the square:
2x 2 + x - 8 = 0
A.
x =
1 +
65
4
or x =
1 -
65
4
B.
x =
- 1 +
65
4
or x =
- 1 -
65
4
C.
x = - 1 or x = 1
D. None of the above
Correct Answer
Option B
Detailed Solution
Solution Details
Given 2x 2 + x - 8 = 0
• 2x 2 + x - 8 = 0
• x 2 +
1
2
x - 4 = 0
• x 2 +
1
2
x +
1
16
= 4 +
1
16
• ( x +
1
4
) 2 =
65
16
• x +
1
4
= ±
65
4
• x =
- 1 ±
65
4
∴ x =
- 1 +
65
4
or x =
- 1 -
65
4
For more info please see
Quadratic Equations
Quadratic Equations
Question 5 of 10
5. Solve for x by completing the square: - 2x 2 - 2x +
2
3
= 0
5. Solve for x by completing the square: - 2x 2 - 2x +
2
3
= 0
5. Solve for x by completing the square:
- 2x 2 - 2x +
2
3
= 0
A.
x =
- 3 +
21
6
or x =
- 3 -
21
6
B.
x = 3 or x = - 3
C.
x =
3 +
21
6
or x =
3 -
21
6
D. None of the above
Correct Answer
Option A
Detailed Solution
Solution Details
Given - 2x 2 - 2x +
2
3
= 0
• - 2x 2 - 2x +
2
3
= 0
• x 2 + x -
1
3
= 0
• x 2 + x +
1
4
=
1
3
+
1
4
• ( x +
1
2
) 2 =
7
12
• x +
1
2
= ±
7
12
• x +
1
2
= ±
7
12
12
12
• x +
1
2
= ±
84
12
• x =
- 6 ±
4 × 21
12
∴ x =
- 3 +
21
6
or x =
- 3 -
21
6
For more info please see
Quadratic Equations
Quadratic Equations
Question 6 of 10
6. Solve for x by completing the square: x 2 - 6x - 39 = 0
6. Solve for x by completing the square: x 2 - 6x - 39 = 0
6. Solve for x by completing the square:
x 2 - 6x - 39 = 0
A.
x =
- 3 + 4
3
or x = - 3 - 4
3
B.
x =
3 + 4
3
or x = 3 - 4
3
C.
x = 9 or x = - 9
D. None of the above
Correct Answer
Option B
Detailed Solution
Solution Details
Given x 2 - 6x - 39 = 0
• x 2 - 6x - 39 = 0
• x 2 - 6x + 9 = 39 + 9
• ( x - 3 ) 2 = 48
• x - 3 = ±
48
• x = 3 ± 4
3
∴ x = 3 + 4
3
or x = 3 - 4
3
For more info please see
Quadratic Equations
Quadratic Equations
Question 7 of 10
7. Solve the following inequality : 5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
7. Solve the following inequality : 5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
7. Solve the following inequality :
5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
A.
x ≤
3
5
or x ≥ 7
B.
3
5
≤ x ≤ 7
C.
x ≥
3
5
or x ≥ 7
D. None of the above
Correct Answer
Option B
Detailed Solution
Solution Details
Given 5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
• 5 ( x 2 - 1 ) ≤ 2 ( 19x - 13 )
• 5x 2 - 5 ≤ 38x - 26
• 5x 2 - 38x + 21 ≤ 0
• ( 5x - 3 ) ( x - 7 ) ≤ 0
• 5x 2 - 38x + 21 = 0 at x =
3
5
and x = 7
+0-0+
||||
|
3
5
7|
We have to find values of x where 5x 2 - 38x + 21 ≤ 0.
∴
3
5
≤ x ≤ 7
+0-0+
||||
|
3
5
7|
For more info please see
Quadratic Equations
Quadratic Equations
Question 8 of 10
8. Solve the following inequality : - 15x 2 + x + 40 ≤ 0
8. Solve the following inequality : - 15x 2 + x + 40 ≤ 0
8. Solve the following inequality :
- 15x 2 + x + 40 ≤ 0
A.
-
5
3
≤ x ≤
8
5
B.
-
8
5
≤ x ≤
5
3
C.
x ≤ -
8
5
or x ≥
5
3
D. None of the above
Correct Answer
Option C
Detailed Solution
Solution Details
Given - 15x 2 + x + 40 ≤ 0
• - 15x 2 + x + 40 ≤ 0
• 15x 2 - x - 40 ≥ 0
• ( 3x - 5 ) ( 5x + 8 ) ≥ 0
• 15x 2 - x - 40 ≥ 0 at x =
5
3
and x = -
8
5
+0-0+
||||
|-
8
5
5
3
|
We have to find values of x where 15x 2 - x - 40 ≥ 0.
∴ x ≤ -
8
5
or x ≥
5
3
+0-0+
||||
|-
8
5
5
3
|
For more info please see
Quadratic Equations
Quadratic Equations
Question 9 of 10
9. Solve the following inequality : 8x ( x + 1 ) ≥ 4 ( 9 - x )
9. Solve the following inequality : 8x ( x + 1 ) ≥ 4 ( 9 - x )
9. Solve the following inequality :
8x ( x + 1 ) ≥ 4 ( 9 - x )
A.
- 3 ≤ x ≤
3
2
B.
- 3 ≥ x ≥
3
2
C.
x ≤ - 3 or x ≥
3
2
D. None of the above
Correct Answer
Option C
Detailed Solution
Solution Details
Given 8x ( x + 1 ) ≥ 4 ( 9 - x )
• 8x ( x + 1 ) ≥ 4 ( 9 - x )
• 8x 2 + 8x ≥ 36 - 4x
• 8x 2 + 12x - 36 ≥ 0
• 2x 2 + 3x - 9 ≥ 0
• ( 2x - 3 ) ( x + 3 ) ≥ 0
• 2x 2 + 3x - 9 ≥ 0 at x =
3
2
and x = - 3
+0-0+
||||
|- 3
3
2
|
We have to find values of x where 2x 2 + 3x - 9 ≥ 0.
∴ x ≤ - 3 or x ≥
3
2
+0-0+
||||
|- 3
3
2
|
For more info please see
Quadratic Equations
Quadratic Equations
Question 10 of 10
10. Solve the following inequality : 5x ( 4x + 5 ) < 4 ( x - 1 )
10. Solve the following inequality : 5x ( 4x + 5 ) < 4 ( x - 1 )
10. Solve the following inequality :
5x ( 4x + 5 ) < 4 ( x - 1 )
A.
-
4
5
< x < -
1
4
B.
1
4
< x <
4
5
C.
x < -
4
5
or x > -
1
4
D. None of the above
Correct Answer
Option A
Detailed Solution
Solution Details
Given 5x ( 4x + 5 ) < 4 ( x - 1 )
• 5x ( 4x + 5 ) < 4 ( x - 1 )
• 20x 2 + 25x < 4x - 4
• 20x 2 + 21x + 4 < 0
• ( 5x + 4 ) ( 4x + 1 ) < 0
• 20x 2 + 21x + 4 = 0 at x = -
4
5
and x = -
1
4
+0-0+
||||
|-
4
5
-
1
4
|
We have to find values of x where 20x 2 + 21x + 4 < 0.
∴ -
4
5
< x < -
1
4
+0-0+
||||
|-
4
5
-
1
4
|
For more info please see
Quadratic Equations