This is the concept of quadratic equations, to find out if the expression is correctly applied we solve the equation given using the quadratic formula;
x=[-b+\-sqrt[b^2-4ac]]/(2a)
Given the equation x^2+5x-8=0
then, a=1,b=5 and c=-8
Applying the formula we get:
x=[-5+\-sqrt(5^2-4*1*(-8))]/(2*1)
x=[-5+\-sqrt(25+32)]/2
x=[-5+\-sqrt57]2
The answer is:
x=[-5+\-sqrt57]/2
