SOLUTION: 4x-y=7 and xy=15 y=15/x 4x-(15/x)=7 multiply everything by x and get 4x^-7x-15=0 when you factor x=-5/4 and x=3

Question 1057021: 4x-y=7 and xy=15 y=15/x 4x-(15/x)=7 multiply everything by x and get 4x^-7x-15=0 when you factor x=-5/4 and x=3

Found 3 solutions by ikleyn, MathTherapy, jenny.rice:
Answer by ikleyn(52765)   (Show Source): You can put this solution on YOUR website!
.

4x - y = 7, (1) xy = 15. (2) From (1), express y = 4x-7 and substitute it into equation (2), replacing y. You will get a single quadratic equation x*(4x-7) = 15. Simplify: 4x^2 - 7x - 15 = 0, = = = . = = 3 ---> y = = = 5. = = = -1.25. ---> y = = = -12. Answer. There are two solutions: (x,y) = (3,5) and (x,y) = (-1.25,-12).

For many other similar solved problems see the lesson
    - Solving systems of algebraic equations of degree 2 and degree 1
in this site.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lesson is the part of this online textbook under the topic "Systems of equations that are not linear".

Answer by MathTherapy(10549)   (Show Source): You can put this solution on YOUR website!

4x-y=7 and xy=15

Answer by jenny.rice(1)   (Show Source): You can put this solution on YOUR website!
4x-y=7 and xy=15 y=15/x 4x-(15/x)=7 multiply everything by x and get 4x^-7x-15=0 when you factor x=-5/4 and x=3

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