a maths 求救!

△≤0
32-4(-2)[-(3k+1)]≤0
9-8-24k≤0
1-24k≤0
24k≥1
k≥1/24

簡單d記

所有case

大過等於或者大過或者細過或者細過等於

delta 都係細過0, 只係如果題目有等於, delta就要加個等號, 即係由細過變成細過或等於 , 咁記好記d!

Consider the coefficient of x²
if coefficient of x² is negative, discriminant greater than 0
if coefficient of x² is positive, discriminant smaller than 0

First of all, you must clarify that this is a quadratic equation or a quadratic function. If this is a quadratic equation, then it must be = 0. And normally you are required to find the value of k such that this equation has real roots (or unreal roots or equal roots). For the equation to have real roots, delta must be equal or greater than 0, for unreal roots, delta must be smaller than 0, for equal roots, delta equals to 0.