i need to know a formula or equation to solve for this. 162 must be the product and sum of x and y
x=x
y=y
xy=162=x+y
refrence sites if possible
MATH HELP!! xy=162=x+y?
2012-06-21 6:18 am
回答 (3)
2012-06-21 6:27 am
✔ 最佳答案
xy = 162x + y = 162
y = 162/x
x + 162/x = 162
x^2 + 162 = 162x
x^2 - 162x + 162 = 0
x = (162 ± √(162^2 - 4(162)))/2 (quadratic formula)
= (162 ± √25596)/2
= 81 ± 9√79
y = 162 - 81 ∓ 9√79
= 81 ∓ 9√79
2012-06-21 1:36 pm
first equation:
xy = x+y
xy - x = y
x (y - 1) = y
x = y / (y-1)
second:
x+y = 168
combine:
y / (y-1) + y = 168
y / (y-1) + y (y-1) / (y-1) = 168
y / (y-1) + (y^2 - y) / (y-1) = 168
y^2 / (y-1) = 168
y^2 = 168 y - 168
y^2 - 168 y + 168 = 0
y = -b +/- sqrt(b^2 - 4ac) / 2a
y1 = 166.994
y2 = 1.006
x1 = 168 - 166.994 = 1.006 (actually x1 = y2)
So, the answer are 166.994 and 1.006, where x and y are interchangeable
xy = x+y
xy - x = y
x (y - 1) = y
x = y / (y-1)
second:
x+y = 168
combine:
y / (y-1) + y = 168
y / (y-1) + y (y-1) / (y-1) = 168
y / (y-1) + (y^2 - y) / (y-1) = 168
y^2 / (y-1) = 168
y^2 = 168 y - 168
y^2 - 168 y + 168 = 0
y = -b +/- sqrt(b^2 - 4ac) / 2a
y1 = 166.994
y2 = 1.006
x1 = 168 - 166.994 = 1.006 (actually x1 = y2)
So, the answer are 166.994 and 1.006, where x and y are interchangeable
2012-06-21 1:23 pm
Just factor it, then see which two factors can be added to equal 162. They would be x = 161.194, y = 1.005.
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