Quadratic Equations

Quadratic Equations - JEE & CBSE

Concepts:


  • Quadratic equation:

Equation in the form of ax2+bx+c=0, where a0

  • Standard form:

Rearranged form of the equation as ax2+bx+c=0

  • Roots of quadratic equations:

Values of x that make ax2+bx+c=0 true


  • Discriminant (D):

Quantity under the square root in the quadratic formula, D=b24ac

  • Determines nature of roots:
  • D>0, real and distinct roots
  • D=0, equal roots
  • D<0, no real roots (complex and conjugate)

  • Quadratic formula: x=b±D2a

Results:


  • Sum of roots: x1+x2=ba

  • Product of roots: x1x2=ca


  • Special Cases:

  • Perfect square: Discriminant is a perfect square, rational equal roots

  • Incomplete quadratic equation: One variable, forms px2±q=0 or ax2=k,k0

  • Applications:

  • Solving quadratic inequalities

  • Maxima and minima problems

  • Sums of squares series

  • Problems involving quadratic relationships.