NumericalHard4 marks
Solve the following quadratic equation 2x² - 5x - 4 = 0 Give your answer correct to three significant figures. (Use mathematical tables for this question)
Topic: Quadratic equations
Previous-year question practice database
Answer
Exam answer
2x² − 5x − 4 = 0.
Here a = 2, b = −5, c = −4.
x = [−b ± √(b² − 4ac)]/(2a) = [5 ± √(25 + 32)]/4 = [5 ± √57]/4.
√57 ≈ 7.550.
x ≈ (5 + 7.550)/4 = 3.1375 or x ≈ (5 − 7.550)/4 = −0.6375.
Correct to three significant figures:
Answer: x = 3.14 or −0.638.
Explanation
Use the quadratic formula after writing the equation in standard form. Round only the final values to three significant figures.
More from Quadratic Equations
The nature of roots of quadratic equation 3x2 − 6x − 3 = 0 are :2026Solve the quadratic equation (x − 2)² − 5x − 3 = 0 and give your answer correct to 3 significant figures.2026The given quadratic equation 3x² + √7x + 2 = 0 has:2025The roots of the quadratic equation px² - qx + r = 0 are real and equal if:2024Solve the following quadratic equation for x and give your answer correct to three significant figures :
2x² - 10x + 5 = 0
(Use mathematical tables if necessary)2024If 3 is a root of the quadratic equation x² - px + 3 = 0 then p is equal to :2023