how to solve this problem using the quadratic formula

Question

x²-x-20=0

Answer 1

x=[-(-1)±√(1²-4×1×(-20))]/2=[1±9]/2=5,-4

or, avoiding the formula x²-x-20=0 factors as (x-5)(x+4)=0

Answer 2

x² - x - 20 = 0

 

The quadratic formula is:

 

x = {-b ± √(b²-4ac)} / 2a

 

Where:

a = the coefficient of the x² term = 1

b = the coefficient of the x term = -1

c = the constant term = -20

 

x = {-(-1) ± √((-1)²-4*1*(-20))} / 2

 

x = (1 ± √81)/2

 

Can you finish it from here?

 

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Note that you can also factor the quadratic equation:

 

x² - x - 20 = 0

 

Factors to:

 

(x-5)(x+4) = 0