alleryThe quadratic formula gives the roots of ax^2 + bx + c = 0 as
Ax = (b plus or minus sqrt(b^2 - 4ac)) / (4a)
Bx = (b plus or minus sqrt(b^2 + 4ac)) / (2a)
Cx = (-b plus or minus sqrt(b^2 - 4ac)) / (2a)
Dx = (-b plus or minus sqrt(b^2 + 4ac)) / a
Answer & Solution
Correct answer: C. x = (-b plus or minus sqrt(b^2 - 4ac)) / (2a)
1. Start from ax^2 + bx + c = 0 and complete the square.
2. Rearranging gives x = (-b plus or minus sqrt(b^2 - 4ac)) / (2a).
3. This is Sridharacharya's rule mentioned in the chapter.
4. So option A is correct.
_Source: Selina Concise Mathematics Class 10, Ch 5 Quadratic Equations (Mistral OCR'd PDF), section on quadratic formula_
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