Question

已知3的X次方=4,3的y次方=2.求9的2x减y的次方加27的x减y的次方的值

Answer 1

3^x=4,3^y=2,

3^x/3^y=3^(x-y)=4/2=2

(3^x)^2=3^2y=16

3^2x/3^y=3^(2x-y)=16/2=8

9^(2x-y)+27^(x-y)=3^2(2x-y)+3^(3(x-y))=8^2+2^3=72