Exercise C Make the subject of these formulae: x 1) 2) 3) 4) Chapter 6: SOLVING QUADRATIC EQUATIONS A quadratic equation has the form . There are two methods that are commonly used for solving quadratic equations: * factorising * the quadratic formula Note that not all quadratic equations can be solved by factorising. The quadratic formula can always be used however. Method 1: Factorising Make sure that the equation is rearranged so that the right hand side is 0. It usually makes it easier if the coefficient of is positive. x2 Example 1 : Solve + 2 = 0 x2 –3x Factorise (x 2) = 0 –1)(x – Either (x 1) = 0 or (x 2) = 0 – – So the solutions are = 1 or = 2 x x Note: The individual values = 1 and = 2 are called the roots of the equation. x x Example 2: Solve 2x = 0 x2 – Factorise: 2) = 0 x(x – Either = 0 or (x 2) = 0 x –
Exercise C Make x the subject of these formulae: 1) 2) 3) 4) Chapter 6: SOLVING QUADRATIC EQUATIONS A quadratic equation has the form . There are two methods that are commonly used for solving quadratic equations: * factorising * the quadratic formula Note that not all quadratic equations can be solved by factorising. The quadratic formula can always be used however. Method 1: Factorising Make sure that the equation is rearranged so that the right hand side is 0. It usually makes it easier if the coefficient of x2 is positive. Example 1 : Solve x2 –3x + 2 = 0 Factorise (x –1)(x – 2) = 0 Either (x – 1) = 0 or (x – 2) = 0 So the solutions are x = 1 or x = 2 Note: The individual values x = 1 and x = 2 are called the roots of the equation. Example 2: Solve x2 – 2x = 0 Factorise: x(x – 2) = 0 Either x = 0 or (x – 2) = 0