兩個數的差等於6, 積等於16, 求這兩個數.

xy=16,x-y=6

x-y=6
x=6+y
y(6+y)=16
y^2+6y-16=0
(y-2)(y+8)=0
y=2,-8
therefore the answer is:
x=-2, y= -8 or x=8, y=2





2006-10-23 11:12:31 補充：
The answer is -2, -8 and 2, 8

8 and 2
8-2=6
8*2=16

這兩個數是8和2

8 and 2

let one of the numbers be x
the other number will be 6+x
x(6+x)=16
x²+6x=16
x²+6x-16=0
(x-2)(x+6)=0
x=2 or x=-6(rejected because 6+(-6)=0)
so the two numbers are 2 and 8

Let X is larger than y

x-y = 6
xy =16
x = 8
y =2