Problem: If 8β 2x=5y+88 \cdot 2^{x}=5^{y+8}8β 2x=5y+8, then, when y=β8,x=y=-8, x=y=β8,x=
Answer Choices:
A. β4-4β4
B. β3-3β3
C. 000
D. 444
E. 888 Solution:
8β 2x=50;β΄23+x=50=1;β΄3+x=08 \cdot 2^{x}=5^{0} ; \quad \therefore 2^{3+x}=5^{0}=1 ; \quad \therefore 3+x=08β 2x=50;β΄23+x=50=1;β΄3+x=0 and x=β3x=-3x=β3. Note: 20=502^{0}=5^{0}20=50, but, otherwise, 2aβ 5a2^{a} \neq 5^{a}2aξ =5a.