help for hw 6th grade

xy=20     (1)

 

x+y=-19     (2)    

 

From (2) we have y = -x -19    (3)

 

Use (3) in (1)

x*(-x - 19) = 20

 

-x^2 - 19x = 20 

 

rearrange

x^2 + 19x + 20 = 0

 

Use the quadratic equation

 

x = (-19 +/- sqrt(19^2 - 4*1*20))/2

 

to obtain:

x₊ = (sqrt(281) - 19)/2

 

x_- = -(sqrt(281) + 19)/2

 

Put these back into (3) to get the corresponding values of y.