SOLUTION: Solve equation: xy = 600 (x + 10) (y - 5) = 600 xy - 5x + 10y - 50 = 600 Not sure how to solve.

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Question 1168628: Solve equation:
xy = 600
(x + 10) (y - 5) = 600
xy - 5x + 10y - 50 = 600
Not sure how to solve.

Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
To form your exercise better, solve the system of equations:


Simplifying the second equation:

and by substitute using the first equation,



and if subtitute for x then


Continuing from that last equation, multiply left and right sides by y.





And if you try to avoid solving a quadratic equation;
and then

the factorization suggests .
You can evaluate x.

Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

Solve equation:
xy = 600
(x + 10) (y - 5) = 600
xy - 5x + 10y - 50 = 600
Not sure how to solve.




(x + 10)(y  -  5) = 600 ------ eq (ii)
 ------- Substituting  for x in eq (ii)

 ------- Multiplying by LCD, y

(y  -  20)(y + 15) = 0
y  -  20 = 0					OR					y + 15 = 0
y = 20						OR 					y = - 15


 ------- Substituting 20 for y in eq (i) 
x = 30



 ------- Substituting - 15 for y in eq (i) 
x = - 40

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