Given the inequality: 3x2≥3 To solve this inequality, we must first solve the corresponding equation: 3x2=3 Solve: Move right part of the equation to left part with negative sign.
The equation is transformed from 3x2=3 to 3x2−3=0 This equation is of the form
a*x^2 + b*x + c = 0
A quadratic equation can be solved using the discriminant. The roots of the quadratic equation: x1=2aD−b x2=2a−D−b where D = b^2 - 4*a*c - it is the discriminant. Because a=3 b=0 c=−3 , then
D = b^2 - 4 * a * c =
(0)^2 - 4 * (3) * (-3) = 36
Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
or x1=1 x2=−1 x1=1 x2=−1 x1=1 x2=−1 This roots x2=−1 x1=1 is the points with change the sign of the inequality expression. First define with the sign to the leftmost point: x0≤x2 For example, let's take the point x0=x2−101 = −1+−101 = −1011 substitute to the expression 3x2≥3 3(−1011)2≥3
363
--- >= 3
100
one of the solutions of our inequality is: x≤−1
_____ _____
\ /
-------•-------•-------
x2 x1
Other solutions will get with the changeover to the next point etc. The answer: x≤−1 x≥1