If x
3+2
73 -
V3 - 2
and y-
73 + 2
value of x2 + y2 + xy
find the
Answers
Answer:
x + y = 18
x*y = 72
So we need whole number factors of 72 that fulfill those conditions.
Factors of 72:
1, 2, 3, 4, 6, 8, 9, 12, 18, 36, 72
Two of those numbers add up to 18 and multiply to make 72:
12 and 6
Let x = 12 and y = 6
x+y = 18
12+6 = 18
18 = 18
x*y = 72
12*6 = 72
72 = 72
So x = 12 and y = 6. Now substitute in the third equation:
(12)^2 + (6)^2 = 144 + 36 = 180
Incidentally, there is also another way to solve this problem:
x + y = 18
x*y = 72
Solve for x in the first equation:
x = 18-y
Now substitute for x in the second equation:
x*y = 72
y(18-y) = 72
Distribute:
-2y^2+18y = 72
This is a qudratic equation, so we should format it as such. Subtract 72 from both sides:
-2y^2+18y - 72 = 0
Divide the all terms by -2:
y^2–18y+72 = 0
Factor:
(y-12)(y-6) = 0
You can see that there are two solutions here, as is the result of a typical quadratic equation. The solutions are 12 and 6, and both of these satisfy the conditions posed by the original problem.