Respuesta :

msm555

Answer:

Solution given:

a=300

and equation is:

x²-40x+a=0

when a=300

x²-40x+300=0

making it a perfect square

x²-2*20x+20²-20²+300=0

(x+20)²-400+300=0

(x+20)²=100

x+20=±10

taking positive

x+20=10

x=10-20

x=-10

taking negative

x+20=-10

x=-10-20

z=-30

when A=300

x=-10 or -30