Answer:
the product of the 2 numbers is 22
Step-by-step explanation:
x² + y² = 80
(x - y)² = 36
=>
x - y = 6
or y - x = 6
let's start with the first one x-y=6
x = 6 + y
=>
(6+y)² + y² = 80
y² + 6y +6y + 36 + y² = 80
2y² + 12y + 36 = 80
2y² + 12y - 44 = 0
y² + 6y - 22 = 0
the solution of a quadratic equation
x = (-b ± sqrt(b² - 4ac))/(2a)
in our case here we have an squadron in y.
a=1
b=6
c=-22
(-6 ± sqrt(36 + 4×22))/2 = (-6 ± sqrt(36+88))/2 =
= (-6 ± sqrt(124))/2 = (-6 ± sqrt(4×31))/2 =
= (-6 ± 2×sqrt(31))/2 = -3 ± sqrt(31)
y1 = -3 + sqrt(31)
y2 = -3 - sqrt(31)
=>
x1 = 6 + -3 + sqrt(31) = 3 + sqrt(31)
x2 = 3 - sqrt(31)
control :
(-3 + sqrt(31))² + (3 + sqrt(31))² = 80
9 - 3 sqrt(31) - 3 sqrt(31) + 31 + 9 +3 sqrt(31) + 3 sqrt(31) + 31 = 80
9 + 31 + 9 +31 = 80
18 + 62 = 80
80 = 80 correct
solving now for y-x=6
delivers exactly the same calculations, just with x and y trading places.
so, the resulting 2 number pairs are the same.
the product of the 2 numbers :
(3 + sqrt(31))(-3 + sqrt(31)) = -9 - 3 sqrt(31) + 3 sqrt(31) + 31 =
= -9 + 31 = 22
(3 - sqrt(31))(-3 - sqrt(31)) = -9 + 3 sqrt(31) - 3 sqrt(31) + 31 =
= 22
so, the product is the same in both cases.
