NumericalModerate3 marks
Solve for x the quadratic equation x² - 4x - 8 = 0. Give your answer correct to three significant figures.
Topic: Quadratic equations
Previous-year question practice database
Answer
Solution diagram
Exam answer
x²−4x−8=0.
x = [4 ± √(16+32)]/2 = [4 ± √48]/2 = 2 ± 2√3.
Using √3≈1.732: x≈5.464 or −1.464.
To three significant figures:
Answer: 5.46 or −1.46.
Explanation
Apply the quadratic formula and round only the final roots.
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