Problem: If xξ =0 or 4 and yξ =0 or 6, then x2β+y3β=21β is equivalent to
Answer Choices:
A. 4x+3y=xy
B. y=6βy4xβ
C. 2xβ+3yβ=2
D. yβ64yβ=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=xyβ6x. Factoring x from the right side of the last equation gives 4y=x(yβ6). Since yξ =6 we can divide both sides of this equation by yβ6 to obtain (D).