 This is the exception; solve them directly. example 1: 4x2 - 36 = 0 4x2 = 36 x2 = 9 x = 3 or -3 x = ±3 Although the last step involves taking the square root of both sides, we use both answers and not just the principal root. Here is the simplest version of this type: example 2: x2 = 25 x = 5 or -5 x = ±5 The answers can be irrational: example 3: 2x2 = 56 x2 = 28 x = √28 or -√28 You can either simplify the radical to get exact answers: x = 2√7 or -2√7 or you can evaluate and round: x ≈ 5.29 or -5.29 Sometimes there aren't any Real answers: example 4: 3x2 + 48 = 0 3x2 = -48 x2 = -16 In grade 9/10 math, we woud say: "Since you can't do the square root of a negative number, the equation has no answer." In grade 11/12 math, recognizing the existance of Imaginary numbers, we would continue: x = ±√-16 x = ±√16√-1 = ±4i where i = √-1 Now let's move on to ax2 + bx = 0 ... |