Problem: If 2x+y4x​=8 and 35y9x+y​=243,x and y real numbers, then xy equals:
Answer Choices:
A. 512​
B. 4
C. 6
D. 12
E. −4
Solution:
2x+y4x​=2x+y22x​=2x−y=8=23∴x−y=3∴x=4,y=1
35y9x+y​=35y32x+2y​=32x−3y=243=35∴2x−3y=5∴xy=4