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To solve , Aarav substitutes into the quadratic formula.
What has he done wrong, and what are the correct roots?

Class 10The Quadratic FormulaQuadratic Equations
  • ANothing is wrong; the equation has no real roots
  • Bb should be −7, so the roots are and −5
  • CHis c is correct, and the roots are and 5
  • DThe 15 must be moved across first, making ; the roots are and −5

Step-by-Step Solution

The formula only applies once the equation reads . Here that means , so , not 15. Then or −5. With the discriminant would be 49 − 120 < 0 and Aarav would wrongly conclude there are no real roots.
Answer: D) The 15 must be moved across first, making ; the roots are and −5

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