What two numbers added together make7 but multiplied make 20?

Answer 1

Let call them x and y

x+y=7 and x*y=20

From the first you get x = 7 -y, put into the second get (7-y)*y=20

-y^2+7*y=20 or y^2-7+20=0

Delta = (-7)^2-4*1*20 = -31

y = (7-i*sqrt(31))/ 2 or y = (7+i*sqrt(31))/ 2

and

x = 7-y = (7+i*sqrt(31))/ 2 or x = (7-i*sqrt(31))/ 2