Problem: If xî€ =0 or 4 and yî€ =0 or 6, then x2​+y3​=21​ is equivalent to
Answer Choices:
A. 4x+3y=xy
B. y=6−y4x​
C. 2x​+3y​=2
D. y−64y​=x
E. none of these
Solution:
Multiplying both sides of the given equation by the least common denominator 2xy yields 4x+6y=xy or, equivalently, 4x=xy−6x. Factoring x from the right side of the last equation gives 4y=x(y−6). Since yî€ =6 we can divide both sides of this equation by y−6 to obtain (D).