NumericalHard4 marks
Solve x² + 7x = 7 and give your answer correct to two decimal places.
Topic: Quadratic equations
Previous-year question practice database
Answer
Solution diagram
Exam answer
x = {0.89, – 7.89}
Explanation
x2 + 7x = 7 ⇒ x2 + 7x − 7 = 0 a = 1, b = 7, c = −7 x = −b ± √b2 − 4aa 2a = −7 ± (−7)2 − 4 × 1 × (−7) 2 × 1 x = −7 ± √49 + 28 2 × 1 = −7 ± √77 = −7 ± 8.775 = −7 + 8.775 , −7 − 8.775 1.775 , −15.775 = 0.8875, −7.8875 x = {0.89, – 7.89} SECTION B (40 Marks) Attempt any four questions from this Section
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