2 The expression a x 2 + b x + c ( quadratic function in one variable ) in the definition of a quadratic function is a polynomial of degree of 2 or second order , or a 2nd degree polynomial , since the highest exponent of x is 2. This expression is called quadratic polynomial or quadratic . If the quadratic is set equal to zero, then the result is a quadratic equation or a second degree equation . The general form of the quadratic equation is ax 2 + bx + c = 0 , where a, b, and c are constants and a ≠ 0.
3 Writing quadratic equation in standard form / general form The general form of the quadratic equation is ax 2 + bx + c = 0 , where a, b, and c are constants and a ≠ 0 . Example 1. Write x 2 = 2x + 2 in standard form . x 2 – 2x – 2 = 0 (standard form) a = 1, b = -2, c = -2
4 Example 2. Write 2x – x 2 + 9 = 0 in standard form. Example 3. Write x 2 = 9 in standard form. ax 2 + bx + c = 0 -x 2 + 2x + 9 = (since the value of a is negative, divide or multiply both sides by -1) = x 2 – 2x – 9 = 0 a = 1, b = -2, c = -9 ax 2 + bx + c = 0 x 2 – 9 = 0 a = 1, b = 0, c = -9 Example 2. Write 2x – x 2 + 9 = 0 in standard form. Example 3. Write x 2 = 9 in standard form. ax 2 + bx + c = 0 x 2 – 9 = 0 a = 1, b = 0, c = -9