Question

若2 的x方减1 等于 a,2的y方减1 等于b ,问2的x方加y方等于多少?

Answer 1

2^(x-1)=a

2^(y-1)=b

2^(x-1) * 2^(y-1)=ab

2^(x+y-2) =ab

2^(x+y) /4=ab

2^(x+y) =4ab

故：选D