Given the inequality:
z2+5z<0To solve this inequality, we must first solve the corresponding equation:
z2+5z=0Solve:
x1=−5x2=0x1=−5x2=0This roots
x1=−5x2=0is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
x0<x1For example, let's take the point
x0=x1−101=
−5+−101=
−5.1substitute to the expression
z2+5z<0z2+5z<0 2
z + 5*z < 0
Then
x<−5no execute
one of the solutions of our inequality is:
x>−5∧x<0 _____
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x1 x2