QQuestion
The nature of the roots of the equation 3x² − 6x − 3 = 0 is:
(a) Real and equal
(b) Real, distinct and rational
(c) Real, distinct and irrational
(d) No real roots
The nature of the roots of the equation 3x² − 6x − 3 = 0 is:
(a) Real and equal
(b) Real, distinct and rational
(c) Real, distinct and irrational
(d) No real roots
(c) Real, distinct and irrational
Explanation:
For 3x² − 6x − 3 = 0:
a = 3, b = −6 and c = −3
Discriminant, D = b² − 4ac
⇒ D = (−6)² − 4 × 3 × (−3)
⇒ D = 36 + 36 = 72
Since D > 0, the roots are real and distinct. Since 72 is not a perfect square, the roots are irrational.
More ICSE Moderate level questions
Solve the quadratic equation (x − 2)² − 5x − 3 = 0 and give your answer correct to 3 significant figures.
The quadratic equation 3x² + √7x + 2 = 0 has: (a) two equal real roots. (b) two distinct real roots. (c) more than two real roots. (d) no real roots.
Solve the quadratic equation 2x² − 5x − 4 = 0. Give your answers correct to three significant figures.
Solve the following quadratic equation for x and give your answers correct to three significant figures: 2x² − 10x + 5 = 0
The difference of two natural numbers is 5 and sum of their reciprocals is . Find the two numbers.
The roots of the equation px² − qx + r = 0 are real and equal if: (a) p² = 4qr (b) q² = 4pr (c) −q² = 4pr (d) p² > 4qr
If 3 is a root of the quadratic equation x2 − px + 3 = 0, then p is equal to: (a) 4 (b) 3 (c) 5 (d) 2
Mr and Mrs Das travelled by car from Delhi to Kasauli, a distance of approximately 350 km. Heavy rain reduced the average speed by 20 km/h and increased the journey time by 2 hours. Find: (a) the original speed of the car. (b) the time taken at the reduced speed.
A man covers a distance of 100 km, travelling with a uniform speed of x km/hr. Had the speed been 5 km/hr more, it would have taken 1 hour less. Find x, the original speed.
Solve the following quadratic equation: x2 + 4x − 8 = 0. Give your answer correct to one decimal place. Use mathematical tables if necessary.
Assertion (A): The 9th term of the G.P. 6, −12, 24, −48, … is positive. Reason (R): (−2)⁸ is positive. (a) A is true and R is false. (b) A is false and R is true. (c) Both A and R are true and R is the correct explanation of A. (d) Both A and R are true but R is not the correct explanation of A.
In the given figure, ABCD is a cyclic quadrilateral. DE is produced to E and ∠CDE = 65°. If x is the angle subtended by chord AC at the centre, then x is: (a) 32.5° (b) 65° (c) 115° (d) 130°