CMA Foundation · Fundamentals of Business Mathematics and Statistics · Quadratic Equations
What are the roots of the equation x^2 - 11x + 28 = 0?
The roots are 4 and 7. The equation factorises as (x-4)(x-7)=0 because 4 times 7 equals 28 and 4 plus 7 equals 11, matching the constant term and the negative of the coefficient of x.
- A4 and 7Correct
- B-4 and -7
- C3 and 8
- D2 and 14
Explanation
Find two numbers with product 28 and sum 11: 4 and 7. So (x-4)(x-7)=0, giving x=4 or 7. Negative roots (-4, -7) would give sum -11, which is the wrong sign for the middle term.
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