SureDenNCERT Solutions Exercise 3
Question 1: Solve the equation x2 + 3 = 0
Answer 1: The given quadratic equation is x2 + 3 = 0
On comparing the given equation with ax2 + bx + c = 0,
we obtain a = 1, b = 0, and c = 3
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 02 – 4 × 1 × 3 = –12
Therefore, the required solutions are
Question 2: Solve the equation 2x2 + x + 1 = 0
Answer 2: The given quadratic equation is 2x2 + x + 1 = 0
On comparing the given equation with ax2 + bx + c = 0,
we obtain a = 2, b = 1, and c = 1
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 12 – 4 × 2 × 1 = 1 – 8 = –7
Therefore, the required solutions are
Question 3: Solve the equation x2 + 3x + 9 = 0
Answer 3: The given quadratic equation is x2 + 3x + 9 = 0
On comparing the given equation with ax2 + bx + c = 0,
we obtain a = 1, b = 3, and c = 9
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 32 – 4 × 1 × 9 = 9 – 36 = –27
Therefore, the required solutions are
Question 4: Solve the equation –x2 + x – 2 = 0
Answer 4: The given quadratic equation is –x2 + x – 2 = 0
On comparing the given equation with ax2 + bx + c = 0,
we obtain a = –1, b = 1, and c = –2
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 12 – 4 × (–1) × (–2) = 1 – 8 = –7
Therefore, the required solutions are
Question 5: Solve the equation x2 + 3x + 5 = 0
Answer 5: The given quadratic equation is x2 + 3x + 5 = 0
On comparing the given equation with ax2 + bx + c = 0, we obtain a = 1, b = 3, and c = 5
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 32 – 4 × 1 × 5 =9 – 20 = –11
Therefore, the required solutions are
Question 6: Solve the equation x2 – x + 2 = 0
Answer 6: The given quadratic equation is x2 – x + 2 = 0
On comparing the given equation with ax2 + bx + c = 0,
we obtain a = 1, b = –1, and c = 2
Therefore, the discriminant of the given equation is
D = b2 – 4ac = (–1)2 – 4 × 1 × 2 = 1 – 8 = –7
Therefore, the required solutions are
Question 7: Solve the equation 
Answer 7: The given quadratic equation is
On comparing the given equation with ax2 + bx + c = 0, we obtain a = 
, b = 1, and c =
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 12 –
= 1 – 8 = –7
Therefore, the required solutions are
Question 8: Solve the equation 
Answer 8: The given quadratic equation is
On comparing the given equation with ax2 + bx + c = 0, we obtain ð‘Ž = 
Therefore, the discriminant of the given equation is
D = b2 – 4ac = 
Therefore, the required solutions are
Question 9: Solve the equation 
Answer 9: The given quadratic equation is
This equation can also be written as 
On comparing this equation with ax2 + bx + c = 0, we obtain a = 
and c = 1
∴ Discriminant (D)=b2-4ac=
Therefore, the required solutions are
Question 10: Solve the equation 
Answer 10: The given quadratic equation is
This equation can also be written as
On comparing this equation with ax2 + bx + c = 0, we obtain a = 
∴ Discriminant (D)=b2-4ac=
Therefore, the required solutions are
